Each season fishermen try to find out which region recently had successful hauls. They monitor social networks, call each other and ask others on the shore.
This app aggregates all data about cod and halibut in one place. If one fisherman puts a marker where they caught a fish, all other users will see it for three days.
While this does not guarantee a successful catch, it can certainly help you to find your prize. There's no sense in hiding your "secret place". Share it with others through this app, and next time someone will share theirs with you.
Also you can share a whale sighting in this app (this could helps scientists in studying migration paths of these majestic creatures) as well as place a "danger" mark where captain needs to pay extra attention or you risk losing a net.