It would be best not to. Every time I've gotten tattoo work done, I always refrained from any activities that I would bake in the sun or to go in a chlorinated pool.
I always waited at least 2 weeks until the scabbing/flaking was over with. I look at it as, since i spent the money to get the tattoo, I didn't want to run the risk of having it fade from the sun hitting the fresh tat, or the chlorine from a pool fading it. Oceans or lakes could also have bacteria in it, and since a fresh tattoo is essentially an open wound until the healing process begins, you run a risk with that as well.
I hated having to make this decision, but I always went the safe route and stayed out of the water/heavy sun, until it was done healing. Since then I always try to get them in the cooler months, when it was to cold or swim, or I was wearing a hoody or some longer clothing over the tattoo.
Hope this helps!