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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 $45 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 $45. The average used price is $37 for those in good overall condition. New and sealed listings currently range from $45 to $53. Based on current trends, this set could be valued near $46 within the next year.

All regions

All regions 68
United States 65
Canada 2

For Sale (New/Sealed)

	(US) IDEAS 40912 Sea Serpent Set NEW GWP SEALED	BrickEconomy Choice $39.99
	(US) IDEAS Sea Serpent 40912 Complete Set 241 Pieces 18+ Box	$39.99 -11.0%
	(US) Sealed & box in excellent shape.	$40.00 -10.9%
	(US) New in box stored in dry and clean room.	$40.00 -10.9%
	(MO) NO PAYPAL FEES New(Sealed)	$41.53 -7.5%
	(US) Ideas Sea Serpent GWP Insider Brand New Factory Sealed 40912 Fast Safe Ship	$41.84 -6.8%
	(US) IDEAS 40912 Sea Serpent New In Sealed Box 2026	$41.99 -6.5%
	(CA) BrickLink store Bricks N' Such	$41.99 -6.5%
	(CA) New in sealed box	$42.00 -6.5%
	(US) BrickLink store Felwater Bricks	$42.00 -6.5%
	(US) IDEAS 40912 Sea Serpent Set NEW GWP SEALED	$42.99 -4.3%
	(US) Boxes have a little shelfware.	$43.00 -4.3%
	(US) NISB, slight shelf wear	$43.62 -2.9%
	(US) BrickLink store Shaghalabaghala	$44.40 -1.1%
	(US) Brand new in sealed box. Comes from pet-free and smoke-free home. I charge actual shi...	$44.49 -0.9%
	(US) BrickLink store BuildingCelebration	$44.90 0.0%
Show 51 more listings
	(US) IDEAS 40912 Sea Serpent Set NEW GWP SEALED	$44.95 +0.1%
	(US) Sea Serpent 40912 - NEW - SEALED - GWP - Castle	$44.95 +0.1%
	(US) BrickLink store Brickmaster Jack's	$44.95 +0.1%
	(US) BrickLink store KToyHobbies	$44.95 +0.1%
	(US) BrickLink store FirstOrderedBricks	$44.98 +0.2%
	(US) Mint Box. Shipped in a box for safe transit.	$44.98 +0.2%
	(US) 40912 Sea Serpent NEW SEALED Gift With Purchase	$44.99 +0.2%
	(US) Ideas Sea Serpent 40912 Limited Edition 241 pcs Set 18+ NEW SEALED	$44.99 +0.2%
	(US) Sea Serpent (40912)	$44.99 +0.2%
	(US) BrickLink store MATT'S EXTRAS	$44.99 +0.2%
	(US) BrickLink store Bigelow's Baltimore Bricks	$44.99 +0.2%
	(US) BrickLink store Athens Block	$44.99 +0.2%
	(US) BrickLink store NewCastle Bricks	$44.99 +0.2%
	(US) BrickLink store Space City Bits and Bricks	$45.00 +0.2%
	(US) 40912 Sea Serpent Ideas GWP Limited Edition Set (New)	$45.00 +0.2%
	(US) IDEAS 40912 Sea Serpent Set NEW GWP SEALED	$45.00 +0.2%
	(US) NSIB	$45.00 +0.2%
	(US) Brand New and Sealed	$45.00 +0.2%
	(US) 40912 Ideas Sea Serpent New Sealed	$45.95 +2.3%
	(US) IDEAS 40912 Sea Serpent Set NEW GWP SEALED	$47.99 +6.9%
	(US) 40912 Sea Serpent Set - New Sealed	$48.99 +9.1%
	(US) Ideas 40912 Sea Serpent Viking GWP Gift With Purchase	$48.99 +9.1%
	(US) 40912 Sea Serpent Viking GWP New Sealed Ships Free	$48.99 +9.1%
	(US) Ideas 40912 Sea Serpent GWP NEW SEALED	$49.95 +11.2%
	(US) IDEAS 40912 Sea Serpent New in sealed box	$49.99 +11.3%
	(US) IDEAS 40912 Sea Serpent Set NEW GWP SEALED 100% complete	$50.00 +11.3%
	(US) 40912 Ideas Sea Serpent Promotional Set 241 pcs 18+ Box 8in x 3.7in	$50.00 +11.3%
	(US) Ideas 40912 Sea Serpent GWP NEW SEALED	$50.00 +11.3%
	(US) Ideas Sea Serpent 40912 Complete Set 241 Pieces Building Set 18+	$50.00 +11.3%
	(US) IDEAS 40912 Sea Serpent Set NEW GWP SEALED	$50.00 +11.3%
	(US) IDEAS 40912 Sea Serpent Set NEW GWP SEALED	$50.99 +13.5%
	(US) Exclusive Ideas Sea Serpent Set 241 Pieces #40912 NEW	$51.99 +15.8%
	(US) Ideas 40912 Sea Serpent Set GWP SEALED IN HAND	$52.00 +15.8%
	(US) Ideas 40912 Sea Serpent - New, Factory Sealed, Unopened	$52.22 +16.3%
	(US) 40912 - Sea Serpent Retro Castle Knights - New Sealed	$52.95 +17.9%
	(US) Sea Serpent 40912 - NEW - SEALED - GWP - Castle	$52.99 +18.0%
	(US) Ideas 40912 Sea Serpent Viking GWP Gift With Purchase NEW SEALED	$52.99 +18.0%
	(US) 40912 Sea Serpent Brand New And Sealed Free Shipping	$54.20 +20.7%
	(US) Ideas 40912 Sea Serpent	$54.94 +22.3%
	(US) Ideas VIP GWP Sea Serpent Brand New Factory Sealed 40912 Limited Edition 1	$54.95 +22.4%
	(US) 40912 Sea Serpent GWP, Perfect Sealed Box	$54.99 +22.4%
	(US) Ideas 40912 Sea Serpent Remake Brand New Factory Sealed	$55.00 +22.5%
	(US) Ideas set 40912 Sea Serpent BRAND NEW Classic Castle viking ship GWP	$55.00 +22.5%
	(US) Ideas 40912 Sea Serpent (set 6057 Castle remake) Limited Edition GWP	$55.99 +24.7%
	(US) Ideas Sea Serpent 40912 Retired 2 Exclusive Knights Minifigs Pirates NEW	$55.99 +24.7%
	(US) 40912 Sea Serpent GWP Castle Black Knights New Sealed Set Promo MISB	$58.00 +29.1%
	(US) 40912 Sea Serpent GWP Sealed FAST SHIP NEW	$59.95 +33.5%
	(US) Ideas Sea Serpent 40912 Sealed	$59.99 +33.6%
	(US) 40912 Sea Serpent GWP NEW Factory Sealed Gift With Purchase	$59.99 +33.6%
	(US) Castle Sea Serpent 40912	$60.00 +33.6%
	(US) IDEAS Sea Serpent Set 40912, Brand New, GWP	$62.98 +40.2%
	(US) GWPC Serpent In Gem Mint Condition Sealed In Box Set 40912	$70.00 +55.9%

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 StockX Bricklink	promotional Value $25.22 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 StockX Bricklink	promotional Value $43.32 Annual growth 5.6% 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 $90.00 Annual growth 20.8% 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 $49.99 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 StockX Bricklink	promotional Value $22.71 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 $54.90 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 $36.42 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 $34.99 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 $20.50 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 37.3% 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 StockX Bricklink	promotional Value $90.00 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 $28.73 Growth +121.2% Annual growth 11.7% 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

$44.91

Used

Value

$37.28

Range

$36.61 - $45.87

Quick Buy

eBay

Buy

Lowest price

$39.99

Highest price

$70.00

Bricklink

Buy

Lowest price

$39.79 (HK)

Highest price

$45.00

*Listings are for new/sealed sets.

Set Predictions

New/Sealed

Today's value

$44.91

1 year forecast

$45.94Medium accuracy

5 year forecast

$50.03

$49

$51

40912 Sea Serpent is projected to be valued between $49 - $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

+10.40%

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 $90.

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)

$44.91

Accuracy

0.962500 Very high

Used

Machine Learning/AI Model

Value (today)

$37.28

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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