Brickipedia
“The Aquashark Dart is the smallest Aquasharks set. Oddly, though it is labeled Hydronauts by LEGO, it is often considered to be an Aquasharks set because of the minifigure it contains. Like most Aquazone sets, there are spare diving flippers on a rack. The sub is piloted by... More Thresher, but his armor is different from that of other Aquasharks. For weapons it has two harpoons, and for propulsion is has a black propeller.”
Full review at brickipedia.fandom.com
BrickEconomy Member Review
“It consists of a small underwater vehicle with a single seat, black propeller, two harpoons, flippers stored on the front, and a control panel. The set includes the minifigure "Thresher," leader of the Aquasharks, featuring a distinct torso design with a shark emblem, blue legs, and mixed headgear. Alternate builds include minor reconfigurations of the vehicle.”