Owning Land on the water

I am in a situation where I have an opportunity to purchase a small lot which is half on the water side and half on the 'marsh' side. At one time there was a camp there with power and water but the hurricanes took care of that.

The issue is that I live in Florida and due to circumstances I am not going to be moving back to Louisiana for 5 or more years. What I am going to do with the land is another story, I may just use it as a launch with some minimal structure or consider building a camp however this is for another day.

What I am trying to understand is the annual maintenance costs I should expect.

Purchase price is known and acceptable and I am inquiring on the annual taxes.

Outside of taxes and lawn maintenance is there anything else I am missing? For example do I need some sort of insurance for land only with no structure?