Memorable adventure from Hammer Films into the fantastic realms of lost lands (though this one is mostly on the water), mostly due to the vibrant photography. It begins a bit unusually, with a bunch of characters whom we will come to know in the middle of a solemn occasion on a ship, obviously in some alien environs. Most of the film is in essence a flashback, as we hear the standard narration for such tales. The journey began with a small complement of crew and passengers, all of whom seem to have a lot of baggage, so to speak - even the captain (Eric Porter), who is engaged in some illegal transport for extra cash. They head out from Africa towards South America but soon there is damage to the ship and most of the people eventually try their luck in a lifeboat. They soon encounter strange seaweed - the threat that most viewers remember best about this film.
I didn't really understand the structure of the story in this first half of the film - the lifeboat soon makes its way back to the same ship and it's as if the story was going nowhere for about 15 minutes, or at least in circles. The seaweed continues to be a problem, there are other creatures, and then there's another memorable image - a woman (Dana Gillespie) walking on the sea of seaweed (she wears special shoes and air balloons). Finally, the stranded people encounter Spanish soldiers who behave as if they're from an earlier century. Passengers are played by Hildegard Knef, Suzanna Leigh, Tony Beckley and Nigel Stock. Much of the film is on the slow side, but there are some eye-opening scenes, including a very grotesque creature to which various victims are tossed to on the orders of a sadistic child ruler. BoG's Score: 6.5 out of 10