◆ What you can do with the Fishing Navi-kun app [Part 1. Display detailed ocean floor map】 Using a detailed seafloor map (bottom topographic map) and the GPS function of your smartphone, you can understand the topography of the ocean floor where your boat is currently floating. It is now possible to infer where fish are hiding based on the topography of the ocean floor, and in some areas, the roots and rapids that are home to fish are also displayed. *There are free and paid options depending