for those thinking about swimming around the pier, water quality here is hard to predict as it comes from the lagoa da tijuca, which can get polluted after heavy rains, however the part of the beach closer to the ocean is generally cleaner.

on this link, the institudo estadual do ambiente - inea provides the suitabilityof several beaches, including 'quebra-mar até pepê' which refers to the beach portion between the pier and praia do pepê, so it can be used to guess water conditions along the pier.