The short answer is no. Tattoos must be fully healed before you can submerge them in any body of water (pools, lakes, oceans, rivers and even bathtubs). For piercings it is advisable to wait until the piercing is healed, but no less than three months before submerging it in any body of water. Disregarding this suggestion will dramatically increase your chances of infection.
For nipple, navel and surface piercings, Tegaderm bandages are a great option! When the bandage is applied properly, they are completely waterproof, and since they are clear, they also allow the jewelry to be visible.