All I can remember that it was in colour and seemed like it must have been made in the 60s/early 70s. Might have been based on Greek or Roman mythology (male characters all in white togas). I saw some of it on TV (definitely one of the main UK terrestial channels) during a Saturday or Sunday afternoon – so must have been U/maybe PG rated and the scene that stuck with me was the last thing I saw. There were male slaves or prisoners trapped in wooden cages on a sandy beach and a huge tsunami heading their way – they were all screaming and shouting and trying to escape but I never saw the wave hit as my parents switched it off!
Have tried Googling/Youtubing to no avail, so hoping someone can reveal the name!
Maybe: Atlantis, the Lost Continent (1961) – http://www.imdb.com/title/tt0054642/