When Commander Ford believes he saw a mermaid at the bottom of the ocean, Captain Bridger orders him to take shore leave.

While on leave, Ford encounters the same woman again and soon finds himself ensnared in a mysterious scientist's unnatural experiment.

Meanwhile, Lucas sneaks away to a party where Julianna and he may go “all the way.”

The seaQuest makes the biggest discovery in Human history when they discover an alien starship entombed in an undersea rock face; trapped there for over a million years.

When an away team goes inside the ship, they find that they might not be the only thing aboard it.

When the crew of seaQuest are tricked into torpedoing a refugee ship containing Westphalen's daughter, Dr. Westphalen, Ford, and Shan are trapped trying to save her.

A brand new power plant which is set to supply energy to the whole world goes wrong and there is a danger of the polar ice caps melting.

Bridger decides he must sacrifice the seaQuest in order to save the world. Meanwhile, Lucas has a reunion of sorts with his father.