Under water you can see the things. But if you are in ocean then the water is salty so it will irritate your eyes. And if you swim in the river then the dirt or plant remains might go in your eyes. And if you swim in swimming pool then chlorine in the water will mess you.
So swimming without googles is a bad idea. Invest in a nice googles which fits properly on your ears. And boom you will have discovered a new world of possibilities.
Go get swimming and enjoy the view beneath. Take your time to swim slowly once in a while.