Sea creature

The sea creature (referred to as both whale and dolphin in the game files) is a creature found in the Commonwealth in 2287.

Characteristics
The creature appears to be a mutated aquatic species.

Biology
The creature likely derives from a species of dolphin that mutated after the Great War. Similarities with dolphins include: the beak, air hole, & a small dorsal fin. Intact specimens can be shot to cause the stomach to explode in a spectacular (and bloody) fashion.

Locations

 * Wreck of the USS Riptide
 * On a boat west of the Beantown Brewery
 * On a boat southwest of the Cambridge Polymer Labs
 * Along the northern coast of Spectacle Island
 * Deep underwater near a shipwreck to the northeast of Fort Strong
 * On a platform covered in debris in Libertalia
 * At the bottom of the rock mountain west of the Rook family house
 * On the beach in front of Sandy Coves Convalescent Home
 * In front of the boardwalk at Revere Beach Station
 * Scattered throughout the docks behind the Shamrock Taphouse

Appearances
The sea creature only appears in Fallout 4.

Behind the scenes
The sea creature found on the boat west of Beantown Brewery is possibly a reference to the original Jaws film. On the boat, a skeleton with a blue jacket, blue bandanna, and a machete can be found with a dead sea creature nearby. The outfit clothing and machete are very similar to the ones worn and used by Quint in the original Jaws film, while the positioning of the sea creature matches that of where Jaws emerges and kills Quint.

If the player character swims underneath the boat, they will also find a diving cage resting on the river bed — another possible reference to Jaws.