Swim paddles (in my opinion) are useful for developing swim-specific strength, especially in the shoulders and lats. I prefer Strokemakers:
Strokemakers are the classic paddle for competitive swimmers. At various points in my swimming career I’ve used Green #1s, Yellow #2s, Red #3s, and Blue #4s. As a Masters swimmer, I use Reds. As an open-water and marathon swimmer, I feel that the strength I develop with these paddles (which some have derogatorily described as “dinner plates”) helps me power through waves and chop in rough-water conditions.
(Note: I have no financial relationship with the company that makes Strokemakers. Every one of their products I own, I’ve paid for. I just like their paddles.)
There’s a catch, though: It’s probably a bad idea to use these paddles as a beginning (or even intermediate-level) swimmer. You can hurt yourself!…