In color, saw it on TV back in 1990 or so. Perhaps 1950s or 60s Pirate Film. The protagonist is actually a young, slender and clean shaved pirate captain. He is able to swing from sail to sail on his ship like tarzan. He even makes an intro talking to the audience at the very beginning saying something “ahoy come lads and lassies”. A few details I remember. A girl is a prisoner on his ship but he helps her rescue his father and releases them which I think angers his crew which mutiny against him. I remember a seen where he, a faithful mate, and a older scientific man are cast off in a life boat with no oars and shackled to the boat. The scientist man makes them flip over the boat so they can actually walk on the sea floor to the nearby shore breathing the air inside the boat under water. Can’t remember much more other than lots of sword fighting.