If you have lakes or can dig them, you can develop public fishing lakes. Normally there are two types: The first is a catch and release, and is solely for the enjoyment of fishing. The customer would pay as they enter and then stay there all day. This could also be combined with camping as mentioned earlier.
The other type is fish and pay. They catch the fish, which are then weighed and paid for. Either option is profitable. You will, of course, need to stock your lakes and ensure you have parking facilities fairly close by.