Neri is a young girl with an affinity for water, the ability to swim long distances and super-human lung capacity.

At the beginning of the series, their mother, Dr. Dianne Bates, has been assigned to ORCA to study whale song in the hopes of facilitating cross-species communication.

A significant portion of the series takes place on ORCA itself, and looks at the activities of its inhabitants, which includes the school-aged children of the resident scientists, such as Jason and Brett.

Dr. Bates rushes out to the ship's deck, grabs the harpoon and tags the whale, albeit missing the intended target area.

At the same time that the Bates family learn about Neri, a rival research organisation, the UBRI Corporation, are introduced.

Headed by the sinister Dr. Hellegren, UBRI have learned that a spacecraft landed somewhere in the vicinity of ORCA, and begin their own search for any personnel that may have survived.

Eventually, they put in play an effort to build the so-called 'ORCA City', an elaborate underwater construction that will likely eradicate much of the natural life on the seabed.

The new character, Kal, proves to be the son of the commander of the vessel, and helps her tap into the ship's memory core.

She finds the ship's log, in which Kal's mother explains that Neri's father was to repair the damage done to Earth's oceans with an advanced device called the Synchronium.

She then dedicates her life to her father's cause, giving her a genuine sense of purpose that she had perhaps lacked earlier in the series.

UBRI tricks Kal into believing that the male should lead (as he had been indoctrinated into the matriarchal social mores of his people), and he creates an alliance with Dr. Hellegren to steal the Synchronium pieces that Neri and Mera have hidden in a secret cave.

Eventually, in the series finale, Jason, Brett, and Neri are able to repulse PRAXIS' efforts and the rebellion, and Earth is saved.

Most of the plots involving the secondary kids on ORCA are reduced in the final season, in order to allow for greater exploration of Neri's home world.

Likewise, the threat of UBRI fades, to be replaced by a new organization, PRAXIS (Preventative Response and eXtraterritorial Intelligence Service) and by rebels on the Ocean Planet.

This group is dedicated to protecting against any threats posed by extraterrestrial life, and its agents come to believe Neri and her people are a problem for Earth.

Internationally, it was broadcast by The Disney Channel in the United States,[1] Discovery Kids in the United Kingdom, YTV and Radio-Canada in Canada, TV Nova and Supermax in the Czech Republic, Sri Lanka Rupavahini Corporation in Sri Lanka, TRT 1 in Turkey, TSI in the Italian part of Switzerland, ZDF and KI.KA in Germany, on RTÉ One and RTÉ Two in Ireland, on RTL 4 in the Netherlands, on (TV2) in Denmark, on NRK and TV2 in Norway, on Fox Kids in Latin America, on TVP 1 (Poland), on TV4 in Sweden, on Canal Panda in Portugal, on Arutz HaYeladim and IETV in Israel, on ZBC in Zimbabwe, on ATV World in Hong Kong, on TV3 in Malaysia, on Channel 2 in Jordan, on Sjónvarpið in Iceland, on Premiere 12 in Singapore, on KBC in Kenya, on NBC in Namibia, on IBC in Thailand, France 2 and Canal J in France, on Duna in Hungary, TV3 in Ghana, on DTV Channel 8 in Guyana and on Channel 33 in the United Arab Emirates.

Common Sense Media gave the show a rating of 4 out of 5 stars, saying "The plot is almost as complex and twisty [as Lost]...the action is crackling and nonstop, the mysteries are many, and the lead character, Neri, is enchanting.