Is there swimming here? Also can you just spend the day here or do you have to spend the night at the camp grounds?

I just spent the day when I came in but I want to come back and rent a cabin as well.

I am not sure if you have to be renting a cabin to use the pool but there are walk down places to get to the water. There are day areas and camping is not required for a day visit. There are often day events as well.

There is not a designated swimming area that I am aware of but you can put in a kayak or paddle board and swim wherever you like. Yes you can spend the day without camping all night.