Shark

The  was a main obstacle in the Shark Stage, and was also found in the Winter Shark Stage. Sharks inflict a large amount of damage to boats, destroying individual blocks with ease and heavily damaging large merged blocks. The Shark can reach up to 30 blocks high. The Shark cannot kill the player, but heavily damages the boat. The Shark acts similar to the Paintbrush obstacle, being a non-solid that damages boats on contact.

Sharks only swim counterclockwise relative to the Shark Stage and will never switch directions. Their fins float on the surface above the water, then strikes up to chomp a boat when it nears the shark, emitting a chomping sound that plays about every half second.

This was, arguably, the most feared obstacle in the whole game, able to shred even the largest boats, cutting boats in half, and having a tendency to destroy every chair.

Trivia

 * The behavior of the Shark is somewhat similar to of a real life shark, but depicts closer to the behavior stereotyped in most shark movies, such as Jaws.
 * While swimming in a "counter-clockwise" fashion, sharks move straight and turn when they hit a wall.