Even today the depths of the ocean remain mysterious, with every deep-sea creature we discover looking more terrifying than the last. In 1926 we knew full well that horrors were awaiting us in the dark below, so apparently we decided to make our diving suits so terrifying that even the most disgusting monsters would flee before us. Just look into that man's shadowy eyes. That's a person who knows he's going to have to punch at least one ichor-spewing fish-man in the face and is fully prepared to do so. And by 1931, terror-suit technology had only grown more advanced.
Imagine being a fish, just minding your own business, when that hulking monster lumbers into view. Now imagine being a human on a beach when it walks out of the waters, looking like it intends to kidnap you and take you to its watery kingdom.