Found this out by accident when walking along the river near pont neuf. There are these little electric boats you can rent for like €35/hour without needing a license or anything.

Way better than the tourist cruise boats because you can go at your own pace and actually stop places. The boats fit 5-6 people so split with friends its pretty reasonable. They give you a basic map and send you off.

You see paris from this completely different angle and can go under all the bridges tourists just walk over. Plus you feel like youre in some french movie or whatever. Just dont try to stand up while moving because apparently thats how you end up in the seine (not that i know from experience or anything).