Trident

 is a gun that fires a beam which can pierce enemies. While reloading, the Trident destroys nearby bullets, and also pushes nearby enemies away.

Trivia

 * If the player has Bionic Leg, Trident receives a 25% damage boost. Replaced with.
 * Under The Sea is a reference to a song from The Little Mermaid (1989 film).
 * The Trident actually fires a small projectile, but it is covered up by the cosmetic beam.
 * The synergy may be a reference to the DC Comic Superhero "Aquaman" who rules an underwater kingdom, wields a trident as a symbol of authority, and has a prosthetic hand.
 * It may also be a reference to the animated Disney film "The Little Mermaid", as the titular mermaid Ariel trades her voice for legs, her father Poseidon wields a trident, and the fish companion summoned by the synergy resembles Ariel's companion, Flounder. Additionally, Ariel sings a song titled "Part of Your World", alluded to in the synergy's name, "Brave New World".