The attraction is located in the Marine Life Institute at the heart of Port Discovery. Scientists at the Institute have created a substance called “Chidiminium” which can conduct electricity and shrink materials, with a demonstration of the technology by a MLI member serving as the attraction's pre-show. This new material is used to safely shrink the SeaRider, a fish-shaped submarine with guests inside.
The SeaRider boasts artificial fish intelligence which allows it to think like a real fish and operate without a pilot. Guests will dive into the sea aboard this adorable fish-submarine and meet marine life such as Nemo, Dory and Marlin, who take guests on a journey through the ocean and encountering numerous characters from the two Finding Nemo films. Similar to Star Tours: The Adventures Continue, there are multiple variations in the ride film with the attraction being divided into roughly five story beats.
Upon being shrunk, we arrive on the Great Barrier Reef. We travel through the reef either in the midst of a game of hide and seek with Dory or swimming with Mr. Ray and his class. It is then that Dory reads the sub's 'nametag' and calls her new 'fish' friend 'Sheila' which everyone else does the whole ride.
As this sequence ends, we are invited to ride on the East Australian Current with the Sea Turtles, with sequences either focusing on Crush or Squirt.
Leaving the Current either drops us off in the Jellyfish Forest where we bounce our way out or in the Kelp Forest where we swim with the Sea Otters.
This leads into a climactic sequence which can include being sucked into the pipes of the Marine Life Institute and evading kids at the touch tank (including Darla) and escaping with the help of Hank or encountering the giant squid at the sunken shipping cargo area which concludes with the group being rescued by Destiny and Bailey.
The attraction wraps up with a "return to the reef" scene where the group is carried and dropped off by Becky and the Loons or following the stingray migration back. The gang says farewell and the SeaRider is brought back to its original size.