Everblue 2 is an adventure game based around scuba diving. It is the sequel to the game Everblue. Endless Ocean is not a sequel to these games, but it features similar gameplay since both Everblue 2 and Endless Ocean were developed by Arika.
The player is Leo, a diver, who sails through a fictional treacherous Caribbean sea with his friends. Their ship sinks in a huge storm and they swim to a nearby island. There, they meet a group of scuba divers called The Amigos. The Amigos salvage valuable items from the sea and sell them for profit. They also help people by finding their missing belongings from sunken shipwrecks.
he player earns money by finding precious materials with their metal, glass, wood, clay, and stone sonars, and looting artifacts from shipwrecks. This money can be used to buy equipment allowing a player access to deeper and more challenging dives. Over time, a player is able to dive through a sunken freighter, a downed airplane, a pirate ship, a sunken luxury liner, a submarine, and an undersea temple.
Source: Wikipedia, "Everblue 2", available under the CC-BY-SA License.