What do you do on a fishing trip? Catching fish might be the obvious answer, but some people just enjoy sitting in a boat on a body of water.

I don't kill things, including fish, but love being out on the boat. Anchor in a secluded cove, get naked, do some swimming and suntanning. Have some snacks and food, go to bed. Repeat the next day.
Sometimes I toss bits of powerbars into the water to watch the baby fish swim around. Stick my gopro in to film them.
Bring a drone to fly around and see what is around you.