ok think this is a 70s film maybe 60s but unsure but it was in colour and saw it when i was a kid on tv in the 90s.

from what i remember it was some sort of adventure monsters movie a team of people were on a small boat run into trouble and near an island and land on the beach then these humanoid monsters that looked like walking seaweed rise up from piles of seaweed on the beach and from the water and start to attack the people and i just remember them fighting on the beach and the monsters were humanoid shaped and draped heavily in real seaweed and kind of greenish colour. Hope you guys can help

Really need help to find out what this movie was i saw it as a young kid in the early 90s it was a movie on tv so heres what i remember:

Large cave and think it was a woman or two woman who had wronged a king or leader and he spoke to them and then they were placed inside the cave as punishment and the cave entrance was bricked up and sealed while the back of the cave was open and very high up so like a cliff edge at the back of the cave and the front entrance was bricked up and sealed.  I assume the prisoners were meant to suffer and starve and eventually jump to their deaths but im unsure as cannot remember anything else but it has bugged me since i was a kid. Think it might have been sort of swords and sorcery type of film but unsure.

Really hope someone can help