This film is a true oddity. In some ways it could have been a good children's film, with oddball pirates and exotic locations, but unfortunately is full of nudity and violence, particularly at its gory climax. Some truly bizarre scenes, such as the pirate who sets light to his hat during raids, a mating ritual involving some kind of mud and an otherwise naked man who carries a leather pouch in front of his genitals when he turns up on a hunt party. Intermingled among this weirdness is some intended comedy, sometimes inappropriate, such as when one pirate sniffs another's feet during a burial at sea. No doubt it is things like this which has earned the film a cult status.
But viewed as an adult film, it makes little sense. This starts early in the film when a gun shop is quite happy to sell a weapon to a 12 year old boy (are US gun laws really this slack?). Next Michael Caine decides to take his son with him on what is a potentially dangerous trip (his son wants Disneyland). Next a wacko pilot (and his pet pig) take Caine and son to Navidad where they are flagged down when trying to land (no explanation for this is given) and the plane crashes. The pilot is remarkably chipper about this. And this is merely the first 20 minutes before we meet the pirates and their peculiar ways.
This bizarreness does make the film strangely watcheable.