Futurama Episodes

A day off from work, the crew aboard the Planet Express Spaceship goes fishing. When Bender fashions a gigantic hook catching a gigantic fish, he causes the ship to sink. Once submerged, the crew finds an ancient sunken city habitated by mermaids and mermen. Fry is the first to contact them – and one of them in a romantic way.
wikipedia.org summary:
A fishing trip over the ocean takes a turn for the worse when a colossal mouth bass pulls the Planet Express ship to the bottom of the sea. There, Fry falls in love with a mermaid named Umbriel with long blonde hair, and the crew discovers the sunken city of Atlanta, Georgia.
imdb.com summary:
When the crew goes fishing, a giant fish pulls the ship under water. There they find an ancient city, where Fry falls in love with Umbriel, a mermaid.