My hero is Jacques -Yves Cousteau, who co-invented Aqualung and pursued underwater exploration around the world. As I cannot afford to have a ship like Cousteau’s famous Calypso to play with, I consistently dive in local waters. I have conducted twice-amonth underwater visual surveys at our research station for over thirteen years. Through those surveys, I have revealed seasonal and inter-annual changes in the fish community. I found that tropical fish are increasing, which suggests warming trends in the Sea of Japan. I also dive in northeast Japan once every two months. Although the entire fish community there was wiped out by the tsunami in March 2011, it has gradually recovered with increasing abundance, species richness, and larger fish.