If you’ll excuse the rather unfortunate pun; who could ask for a finer example of schlock than a sea-man rape movie from a Roger Corman studio?!
‘Humanoids from the Deep’ has your usual picturesque-seaside-town-incorporating-nasty-industrialists kinda story: after a series of mysterious attacks and killings torment the poor townsfolk, the source is traced back to the genetic experiments of a company scientist.
Cue: hunt for the highly sexed mermen, culminating in an absolutely magnificent mega-assault on the town fair. Fun, well paced and non-challenging entertainment.