You certainly can't accuse the makers of this late 60s Hammer adventure, an adaptation of a non-Satanic novel by Dennis Wheatley, of dullness. Not with explosions, giant scorpions, hurricanes, man-eating seaweed, smuggling, mutiny, and religious maniacs in pointy hats - and that's not counting the shifty motives of the passengers. What you can accuse them of, however, is having insufficient resources to bring all this incident to the screen above the level of a Troughton-era Doctor Who or a Saturday matinee of the Warlords Of Atlantis ilk (which, curiously, it would never have been: the BBFC gave The Lost Continent an X back in 1968 and it's now a 12 on DVD).
En route from Freetown, Sierra Leone to Caracas, Venezuela, an old steamer captained by Eric Porter carries not just a motley assortment of "colourful" characters but an illegal cargo of explosive phosphorus. Forced to abandon ship somewhere in the Sargasso Sea after half the crew have mutinied and the ship starts taking on water, the survivors find themselves first drifting, then trapped in a huge growth of carnivorous seaweed and dragged back to their similarly imprisoned old vessel: stuck in a graveyard of wrecks dating back centuries.... and ruthlessly ruled over by the descendants of Spanish conquistadores.
There's a giant octopus, a giant crab and a giant scorpion, not to mention the seaweed, but this was in the days before CGI (and indeed in the days before those hokey Doug McClure movies) and so the monster effects are undeniably substandard to the point of giggles, particularly in the scene where the crab fights the scorpion. Are they cardboard or polystyrene? The music score is too loud and inappropriate - the movie even begins with a pop song! But the film moves at a rate of knots, has plenty going on, and is stuffed with familiar faces - James Cossins, Suzanna Leigh, Tony Beckley, Nigel Stock and Hammer regular Michael Ripper. Sadly, the technical tattiness counts too much against the good points, and it's mildly interesting at best. Perhaps it's due for a remake?