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Sets
Ideas
Promotional
Sea Serpent

40912 LEGO Ideas Sea Serpent

Name: LEGO Ideas Sea Serpent
Brand: LEGO
SKU: 40912-1
Availability: InStock
Rating: 4.80 (14 reviews)

Images 5Description 1

LEGO 40912 Sea Serpent is a Ideas set currently valued at $44 for new and sealed sets. The set retired in July 2026 with annual appreciation averaging 2.30% since. On the used market, values range from $37 to $46 based on condition. Secondary market prices for new and sealed sets typically fall between $45 and $55.

Set Value (New/Sealed)

This chart represents the current new/sealed value of the set Sea Serpent since July 2026. Medium accuracy

LEGO 40912-1 Sea Serpent is an Ideas Promotional set released in 2026, containing 241 pieces and 2 minifigures. The gift-with-purchase model is a modern remake of 6057 Sea Serpent from the 1992 Castle range and was based on the winning entry in the LEGO Ideas A Twist of Nostalgia challenge. It recreates a Black Knights ship with a black hull, blue railings, brown deck details, a front-mounted cannon, oars, shields, and an exclusive fabric sail printed with a red Sea Serpent emblem. The two Black Knights minifigures include helmets, weapons, updated shields, and torso designs reused from 21358 Minifigure Vending Machine.

A new and sealed Sea Serpent is currently valued at around $44. The average used price is $37 for those in good overall condition. New and sealed listings currently range from $43 to $50. Based on current trends, this set could be valued near $45 within the next year.

All regions

All regions 104
United States 100
Canada 2

For Sale (New/Sealed)

	(US) 40912 Sea Serpent Upgrade Pack - Black Knight Minifigures Printed On LEGO	BrickEconomy Choice $35.00
	(US) IDEAS 40912 Sea Serpent New In Sealed Box 2026	$37.79 -14.5%
	(CA) BrickLink store Bricks N' Such	$38.49 -12.9%
	(US) NISB, pictures available upon request	$39.00 -11.8%
	(US) BrickLink store RedRockBricks	$39.95 -9.6%
	(US) Ideas 40912 Sea Serpent GWP New, Factory Sealed, Unopened	$39.99 -9.5%
	(US) IDEAS Sea Serpent Set 40912 GWP Brand New	$39.99 -9.5%
	(US) 40912 Sea Serpent Viking \| Brand New	$39.99 -9.5%
	(US) Sealed -	$39.99 -9.5%
	(US) Ideas - Sea Serpent (40912) - New Sealed - Exclusive Fast Shipping	$39.99 -9.5%
	(US) Ideas Sea Serpent 40912 Limited Edition 241 pcs GWP NEW AND SEALED	$39.99 -9.5%
	(US) IDEAS 40912 Sea Serpent Set NEW GWP SEALED	$39.99 -9.5%
	(US) Ideas Sea Serpent 40912 Complete Set 241 Pieces 18+ Box	$39.99 -9.5%
	(US) Brand New LEGO Ideas 40912 Sea Serpent Complete Set 241 pcs	$40.00 -9.5%
	(US) BrickLink store 5-to-0 Bricks	$40.00 -9.5%
	(US) BrickLink store Upsilant	$40.00 -9.5%
	(US) NISB	$40.00 -9.5%
	(US) NSIB	$40.00 -9.5%
	(US) BrickLink store Insert Clever Store Name	$41.00 -7.3%
	(US) NEW Sealed In Box - Box in great condition, smokefree adult collector.	$41.99 -5.0%
	(US) Slight dent to one corner of the box. Message for pics.	$41.99 -5.0%
Show 82 more listings
	(US) Ideas: Sea Serpent (40912) 241 pcs 18+ Complete Set - Box	$42.00 -5.0%
	(CA) New in sealed box	$42.00 -5.0%
	(US) BrickLink store Felwater Bricks	$42.00 -5.0%
	(MO) NO PAYPAL FEES New(Sealed)	$42.22 -4.5%
	(US) Ideas 40912 Sea Serpent GWP New Factory Sealed Unopened Limited	$42.70 -3.4%
	(US) Box is in Excellent Condition.	$42.95 -2.9%
	(US) 40912 Sea Serpent - New - GWP Promo - 241 pcs - Castle Medieval Knights	$42.98 -2.8%
	(US) BrickLink store Sixx Bricks	$42.99 -2.8%
	(US) Ideas 40912 Sea Serpent GWP New, Factory Sealed, Unopened	$43.00 -2.7%
	(US) BrickLink store Goforth Bricks	$43.00 -2.7%
	(US) Boxes have a little shelfware.	$43.00 -2.7%
	(US) BrickLink store Matt's Wall Of Bricks	$43.20 -2.3%
	(US) Sea Serpent	$43.98 -0.5%
	(US) 40912 Sea Serpent New Factory Sealed	$43.99 -0.5%
	(US) Sealed	$43.99 -0.5%
	(US) BrickLink store Toast's truckload	$43.99 -0.5%
	(US) NISB. Box is in perfect condition	$44.00 -0.5%
	(US) 40912 Ideas Sea Serpent Promotional Limited Edition Mint Box	$44.00 -0.5%
	(US) IDEAS Sea Serpent Pirate Ship Set #40912 GWP 2 Minifigs Perfect Box	$44.00 -0.5%
	(US) new and sealed	$44.08 -0.3%
	(US) BrickLink store Shaghalabaghala	$44.40 +0.4%
	(US) Brand new in sealed box. Comes from pet-free and smoke-free home. I charge actual shi...	$44.49 +0.6%
	(HK) In stockPerfect condition. Can be shipped by 20GP, 40GP, 40HQ, Air. Please ask for sh...	$44.63 +1.0%
	(US) BrickLink store BuildingCelebration	$44.90 +1.6%
	(US) BrickLink store KToyHobbies	$44.95 +1.7%
	(US) BrickLink store CTM's Shop	$44.96 +1.7%
	(US) BrickLink store FirstOrderedBricks	$44.98 +1.7%
	(US) New LEGO Castle 40912 Sea Serpent GWP Dragon Knight Boat	$44.99 +1.8%
	(US) 40912 Ideas Sea Serpent - New Sealed Retired	$44.99 +1.8%
	(US) IDEAS 40912 Sea Serpent Set NEW GWP SEALED	$44.99 +1.8%
	(US) Ideas Sea Serpent Knights Ship GWP Promo Set 40912 241 Pieces New/Sealed	$45.00 +1.8%
	(US) Ideas Sea Serpent (40912) Limited Edition Promotional Set 241 pcs 18+ Box	$45.00 +1.8%
	(US) New Sealed Retired LEGO Ideas 40912 Sea Serpent Set 241Pcs Ship Fast	$45.88 +3.8%
	(US) IDEAS Sea Serpent Set 40912 Brand New Sealed ship worldwide in extra Box	$46.95 +6.2%
	(US) Ideas 40912 Sea Serpent GWP Brand New Sealed	$46.99 +6.3%
	(US) Ideas Sea Serpent 40912 241pc Set 18+ Box Brick Separator Knight	$47.00 +6.3%
	(US) Ideas Sea Serpent Knights Ship GWP Promo Set 40912 241 Pieces New/Sealed	$47.99 +8.6%
	(US) Ideas 40912 2026 Sea Serpent Promotional 241 pcs Complete Retired	$48.00 +8.6%
	(US) Ideas 40912 Sea Serpent GWP New, Factory Sealed, Unopened	$48.00 +8.6%
	(US) Ideas Limited Edition Sea Serpent 40912 Building Set 241 pcs 18+	$48.50 +9.7%
	(US) IDEAS 40912 Sea Serpent Set NEW GWP SEALED	$48.95 +10.7%
	(US) Ideas 40912 Sea Serpent Set GWP - New & Sealed	$49.00 +10.8%
	(US) Ideas 40912 Sea Serpent GWP Castle Black Knights Remake 6057 NEW SEALED	$49.00 +10.8%
	(US) 40912 Sea Serpent Brand New And Sealed Free Shipping	$49.95 +13.0%
	(US) NEW SEALED LEGO 40912 Sea Serpent - RETIRED Ideas Promotional 2026	$49.95 +13.0%
	(US) Ideas 40912 Sea Serpent GWP NEW SEALED	$49.95 +13.0%
	(US) Ideas Sea Serpent 40912 Limited Edition 241 pcs Set 18+ NEW SEALED	$49.99 +13.1%
	(US) Ideas 40912 Sea Serpent Boat GWP -NEW	$49.99 +13.1%
	(US) Ideas 40912 Sea Serpent GWP New, Factory Sealed, Unopened	$49.99 +13.1%
	(US) Ideas 40912 Sea Serpent Viking GWP Gift With Purchase -NEW	$49.99 +13.1%
	(US) Ideas 40912 Sea Serpent Viking GWP Gift With Purchase	$49.99 +13.1%
	(US) Ideas 40912 Sea Serpent GWP Castle Black Knights Remake 6057 NEW SEALED	$49.99 +13.1%
	(US) IDEAS 40912 Sea Serpent Set Brand New GWP Factory Sealed x1	$49.99 +13.1%
	(US) 40912 Sea Serpent New Factory Sealed	$49.99 +13.1%
	(US) Sea Serpent (40912) GWP	$49.99 +13.1%
	(US) Ideas 40912 Sea Serpent NEW SEALED	$49.99 +13.1%
	(US) 2026 Lego Sea Serpent GWP 40912 New Sealed	$49.99 +13.1%
	(US) Ideas Sea Serpent 40912 Limited Edition 241 pcs Set 18+ NEW SEALED	$49.99 +13.1%
	(US) Castle: 40912 Sea Serpent GWP New Sealed	$49.99 +13.1%
	(US) Ideas 40912 Sea Serpent Viking GWP Gift With Purchase -NEW	$49.99 +13.1%
	(US) 40912 Ideas Sea Serpent GWP with 241 PCS BRAND NEW SEALED	$49.99 +13.1%
	(US) Ideas 40912 Sea Serpent GWP 241pc NEW SEALED	$49.99 +13.1%
	(US) IDEAS 40912 Sea Serpent Set NEW GWP SEALED	$50.00 +13.1%
	(US) Ideas 40912 Sea Serpent Set GWP SEALED IN HAND	$50.00 +13.1%
	(US) IDEAS Set # 40912 "Sea Serpent": New - Factory Sealed	$50.00 +13.1%
	(US) Ideas Sea Serpent 40912 NEW Factory Sealed 241pc Ship Set 2 Minifigs	$51.00 +15.4%
	(US) Ideas 40912 Sea Serpent GWP NEW SEALED - Free Shipping	$53.99 +22.1%
	(US) 40912 Sea Serpent GWP NEW Factory Sealed Gift With Purchase	$54.99 +24.4%
	(US) Ideas 40912 Sea Serpent GWP Limited Edition Brand New In Hand Ready To Ship	$55.00 +24.4%
	(US) 40912 Ideas Sea Serpent - New Sealed Retired	$55.00 +24.4%
	(US) Ideas set 40912 Sea Serpent BRAND NEW Classic Castle viking ship GWP	$55.00 +24.4%
	(US) IDEAS Sea Serpent Set 40912, Brand New, GWP pre-order	$55.00 +24.4%
	(US) Ideas 40912 Sea Serpent Remake Brand New Factory Sealed	$55.00 +24.4%
	(US) Ideas 40912 Sea Serpent (set 6057 Castle remake) Limited Edition GWP	$55.99 +26.6%
	(US) 40912 Sea Serpent- Castle - Viking - Lego Ideas \| Brand New Sealed	$57.99 +31.2%
	(US) 40912 Sea Serpent GWP Castle Black Knights New Sealed Set Promo MISB	$58.00 +31.2%
	(US) IDEAS 40912 Sea Serpent & Hot Chocolate Stand 40776 both Brand New	$59.00 +33.5%
	(US) IDEAS Sea Serpent Building Set 40912 (241 pcs)	$60.00 +35.7%
	(US) IDEAS Sea Serpent Set 40912, Brand New, GWP	$62.98 +42.5%
	(US) Sealed LEGO IDEAS Sea Serpent Set 40912 Retro Lego Shop Insider Promo In-Hand	$64.95 +46.9%
	(US) IDEAS 40912 - SEA SERPENT - SEALED BRAND NEW UNOPENED	$69.99 +58.3%
	(US) GWPC Serpent In Gem Mint Condition Sealed In Box Set 40912	$70.00 +58.3%
	(US) Castle: 40912 Sea Serpent GWP New Sealed	$74.95 +69.5%

Sales Distribution (Last 90 Days)

This chart shows the distribution of sales for the past three months of new/sealed 40912 Sea Serpent.

Sets in Ideas / Promotional


	40487 Sailboat Adventure Theme / Subtheme Ideas / Promotional Year 2021 Pieces / Minifigs 330 / 2 Availability Retired Buy this set at Amazon eBay Bricklink	promotional Value $28.15 Annual growth 39.3% I own this set I want this set

	40595 Tribute to Galileo Galilei Theme / Subtheme Ideas / Promotional Year 2023 Pieces / Minifigs 307 / 1 Availability Retired Buy this set at Amazon eBay Bricklink	promotional Value $45.64 Annual growth 6.0% I own this set I want this set

	40698 Books Are My Passion Theme / Subtheme Ideas / Promotional Year 2024 Pieces 285 Availability Retired Buy this set at eBay Bricklink	promotional Value $91.78 Annual growth 20.6% I own this set I want this set

	40788 Friendly Snails Theme / Subtheme Ideas / Promotional Year 2025 Pieces 264 Availability Retired Buy this set at eBay Bricklink	promotional Value $36.22 I own this set I want this set

	40566 Ray the Castaway Theme / Subtheme Ideas / Promotional Year 2022 Pieces / Minifigs 239 / 1 Availability Retired Buy this set at Amazon eBay Bricklink	promotional Value $23.72 Annual growth 32.2% I own this set I want this set

	40896 The X-Files Scully's Lab Theme / Subtheme Ideas / Promotional Year 2026 Pieces / Minifigs 221 / 1 Availability Retired Buy this set at eBay Bricklink	promotional Value $91.53 I own this set I want this set

	40786 Micro Command Center Theme / Subtheme Ideas / Promotional Year 2025 Pieces / Minifigs 214 / 1 Buy this set at eBay Bricklink	promotional Value $34.99 I own this set I want this set

	40789 Flying Moon Car Theme / Subtheme Ideas / Promotional Year 2025 Pieces / Minifigs 211 / 2 Availability Retired Buy this set at Amazon eBay Bricklink	promotional Value $32.00 Annual growth 35.2% I own this set I want this set

	40533 Cosmic Cardboard Adventures Theme / Subtheme Ideas / Promotional Year 2022 Pieces / Minifigs 203 / 1 Availability Retired Buy this set at Amazon eBay Bricklink	promotional Value $20.06 Annual growth 31.3% I own this set I want this set

	40448 Vintage Car Theme / Subtheme Ideas / Promotional Year 2021 Pieces / Minifigs 189 / 2 Availability Retired Buy this set at Amazon eBay Bricklink	promotional Value $25.99 Annual growth 36.4% I own this set I want this set

	40773 The Goonies The Walshes' Attic Theme / Subtheme Ideas / Promotional Year 2025 Pieces / Minifigs 179 / 2 Availability Retired Buy this set at eBay Bricklink	promotional Value $81.71 I own this set I want this set

	40335 Space Rocket Ride Theme / Subtheme Ideas / Promotional Year 2019 Pieces / Minifigs 154 / 1 Availability Retired Buy this set at Amazon eBay Bricklink	Retail $12.99 Value $27.26 Growth +109.9% Annual growth 10.7% I own this set I want this set

My Collection

I own this set

I want this set

Set Details

Set number

40912-1

Name

Sea Serpent

Theme

Ideas

Subtheme

Promotional

Year

2026

Released

July 7, 2026

Retired

July 14, 2026

Availability

Retired

Pieces

241

Minifigs

Set Pricing

Retail price

Free promotional

New/Sealed

Value

$44.21

90-day change

9.52%

Used

Value

$36.69

Range

$36.61 - $45.87

Quick Buy

eBay

Buy

Lowest price

$35.00

Highest price

$74.95

Bricklink

Buy

Lowest price

$38.49 (CA)

Highest price

$44.98

*Listings are for new/sealed sets.

Set Predictions

New/Sealed

Today's value

$44.21

1 year forecast

$45.23Medium accuracy

5 year forecast

$49.25

$48

$51

40912 Sea Serpent is projected to be valued between $48 - $51 within five years.

Insights

A gift-with-purchase promotional release from the Ideas line in 2026, Sea Serpent (40912) draws on early-1990s Black Knights nostalgia and a reworking of the 6057 Sea Serpent, and its single-year promo run tightens supply while a remake-linked design keeps upside moderate rather than exceptional.

Set Facts

It was inspired by LEGO 6057 Sea Serpent from the 1992 Castle range.
The model includes two Black Knights minifigures with updated shields and reused torso designs from 21358 Minifigure Vending Machine.
The set includes an exclusive fabric sail element decorated with the Sea Serpent emblem.
GWP is available to LEGO Insiders starting July 7th through July 12th with purchases of $180 or more.
Sea Serpent was designed by LEGO designer Mel Caddick.

Barcodes

UPC

673419426343

EAN

5702018071908

Sea Serpent Reviews

14 reviews

4.8

Collectors

Investors

Jays Brick Blog

“This model is a modern remake of 6057 Sea Serpent, which was released in 1992, and is likely a set that many of us have fond memories of playing. LEGO Ideas turned this concept into a model, as it was the winner of the A Twist of Nostalgia challenge, with HallowedBrick02’s... More Sea Serpent emerging triumphant amongst a field of retro-themed Ideas!”

Full review at jaysbrickblog.com

Brick Fanatics

“While 40912 Sea Serpent mirrors the overall shaping of the original submission pretty closely, there are still quite substantial changes to both the stern and bow when you look a little closer. Starting from the back of the ship, the squared-off modular stern now makes use... More of hinge plates to angle the side walls, which swing open to allow for internal access (rather than removing the roof).”

Full review at www.brickfanatics.com

Subtheme Analysis

Ideas / Promotional

Sets

Years

2019 - 2026

Annual growth

+10.71%

Community Stats

Sea Serpent currently ranks #8 out of the top most owned sets in Ideas Promotional.

#1Ray the Castaway

#2Sailboat Adventure

#3Cosmic Cardboard Adventures

#4Vintage Car

#5Tribute to Galileo Galilei

#8Sea Serpent

#9Micro Command Center

#10Flying Moon Car

About Ideas Promotional

The LEGO Ideas theme, which started in 2008 as an offshoot of the Japanese website Cuusoo, then formally known as LEGO Cuusoo, is based around a website which allows users to submit ideas for LEGO products to be turned into potential sets available commercially. If fellow users in the LEGO Ideas community up vote the project to 10000 then LEGO Group has a committee which votes on whether to build the set and release it. If the project is approved and cleared for production, it is developed and later released as an official set under the "LEGO Ideas" banner and the original designer receives 1% of the royalties and a number of free sets. Typically, a few projects are approved a year and most are rejected due to various restrictions.

Promotional was introduced in 2019 and currently consists of 13 sets. As of today, 40698 Books Are My Passion is the most valuable Promotional set with an estimated new/factory sealed value of $92.

Ride a wave of nostalgia with the LEGO Ideas Sea Serpent (40912) building set for adults. Inspired by the Sea Serpent set first released in 1992, this reboot won the LEGO Ideas A Twist of Nostalgia design competition. Packed to the gunwales with details, this model ship kit includes a fabric sail, moving rudders and a cargo hold, plus 2 knight minifigures ready for high-seas adventure. Unlock a core memory for adult LEGO fans and collectors with this great gift idea. Set contains 241 pieces.

SHIP BUILDING SET Unwind with the LEGO Ideas Sea Serpent (40912) building kit for adults, a reboot of the 1992 Sea Serpent and the winner of the LEGO Ideas A Twist of Nostalgia competition

AWASH WITH DETAILS To capture the wind, and an authentic feel, this model ship includes a fabric sail, a modular stern, moving rudders, flags and a cargo hold

MEDIEVAL SWASHBUCKLERS Rekindle memories of endless play with 2 knight minifigures that bring the scene to life and spark nostalgic...

Set Pricing Models

BrickEconomy uses a number of methods to determine the value of a set.

New/Sealed

Machine Learning/AI Model

Value (today)

$44.21

Accuracy

0.962500 Very high

Used

Machine Learning/AI Model

Value (today)

$36.69

Value (low range)

$36.61

Value (high range)

$45.87

Accuracy

0.907500 High

To learn more about how we calculate pricing and forecasting, check out our article on BrickEconomy’s Approach to LEGO Pricing and Future Value Predictions.

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