Shamu's Deep Sea Adventures is an action game where players control Shamu the killer whale on a quest to save the SeaWorld theme park from the Greek god Poseidon, who plans to replace it with the lost city of Atlantis and take over the world.
The Game Boy Advance version of Shamu's Deep Sea Adventures plays differently compared to other versions. Players guide Shamu across various levels using the control pad or stylus to swim, dash, defeat enemies, and break objects. The game focuses on collecting crystals to keep Shamu healthy from enemies like puffer fish, sea anemones, and the Kraken. Voice acting is absent in this version, instead using dialogue boxes for each character.
Each level contains crystals, Atlantis tablets, treasure chests, and temporary objective items that Shamu can collect and use later. The game also features a photo gallery with every fourth chest unlock, containing a special picture.