When you're swimming in a pool or lake, you're practically naked already, so why not slip off your bathing suit and get it on? But, wait: is it safe to have sex in water?
Not exactly. Lake, river, ocean, and pond water all contain bacteria. Having sex can introduce that bacteria into your vagina, which could put you at risk for infections that you don't want up there. Pool water, on the other hand, contains chemicals that could irritate your lady business.
Aside from health risks, the logistics just aren't with you on this one. Since lubrication is key when it comes to sex that feels good, you don't want to end up all washed out (literally). The water dissipates your natural moisture, so you're left with friction-filled sex that won't last long. What's worse is that if you're using a condom, the friction could cause a tear, and you won't be protected from pregnancy or STIs if the condom breaks.
What about sex while taking a bath or shower together?
Moving from smooching to screwing in the bath seems like a lovely plan, but the same lubrication problem you have in other bodies of water will arise in a bath, too. So what about doing it in the shower? Again, the water will wash away the wetness you make naturally, and we know that sex without enough lubrication feels awful. You could move to the end of the shower where the water isn't beating down, but you'll just end up chilly and with sore muscles from trying to have sex while standing.
My advice? Sex + water = no fun. So make love without the water.