While on a cruise with their grandfather, the Alden children help discover who is behind the mysterious troubles of the ship--disconnected phone lines, engine trouble, a man overboard--and still have fun sightseeing, eating, and swimming.

"Teen sleuth Sammy Keyes solves a classic locked-room mystery aboard a cruise ship"--Provided by publisher.

"Berkeley and her best friend, Garth, live on an old cruise ship, scavenging for supplies from the drowned cities left behind on the ocean floor after the sea swallowed up all the land. They think they've seen every kind of aquatic creature, but they never expected to find sea monsters... After awakening a Hydra, Berkeley and Garth are sent to live on a submarine, where they study and hunt sea monsters. But the Hydra wants revenge on their home ship--and...

Daisy and Hazel leap into action when a murder is committed on their cruise along the River Nile in Egypt.

Mr Penguin is boarding a luxury cruise ship. He doesn't like water, and he can't swim, but his friend Colin is performing with the Ladies Choir on board - and anyway, Mr Penguin feels like a rest after some busy Adventuring. What's more, fish finger sandwiches are apparently available twenty-four hours a day. Heaven! But despite the glamorous film stars and party atmosphere, Mr Penguin can't help but feel that something shifty is happening on board....

A young man joins an ocean cruise on which some bad-mannered pigs create disaster while on board, and when the man returns home, a great surprise awaits him.

After Alex leaves the island, and Selkie the sea lion is kidnapped, Nim accidentally stows away on the cruise ship that took Selkie, in the hopes of rescuing her and bringing Alex back.

The Kingdom Keepers have their hands full when, during the inaugural cruise of the Disney ship, Fantasy, to exotic locations, they discover that the Overtakers have infiltrated the cast, stolen a journal that belonged to Walt Disney himself, and plan to unleash a powerful evil, the Chernabog.

Chato and Novio win a cruise but are disappointed to find that everyone else on board is a dog, and things go from bad to worse when the dogs party themselves sick and it is up to the cats to find help.