In my opinion, you should always prioritize looking for environments with a good view of the water. You can migrate between peninsulas (Thais Surroundings) or try to do this on islands.
An example would be the 3 ice islands (Folda, Senja and Vega), you can create a cycle of using sqms of water on these 3 islands, giving enough time (30 minutes) for each water floor to renew the possibilities of fishing and training your fishing. Remember that fishing in a protection zone doesn't work, your skill won't go up and you won't get any fish.