In the pool, there is a high chance of being found especially if its a public pool that you're speaking of. This is even the case in private pools in your own backyard, its always unsure what will happen after drowning in a pool.
As for the ocean. You won't be found as long as you're washed up back to shore. Which is preferable, for most people. But please remember, whatever you choose, always prepare yourself with some things to avoid being saved by SI. eg. weights, handcuffs or something to tie yourself with. If you want extra elaboration, ask.