For me the best way to get coins is to get the gost shark (it doesn't cost that much and is really powerful) and go to mahi mahi area, kill them until you are level 3, then go to the Hammer head area and kill them until you are level 10, then go to the whale shark area ( because they give a lot of meat and more meat=more coins) and in 5 minutes, you'll have 1000 coins and you'll also be over level 50 and then you can kill the sperm whale (who really needs a buff) and kill him untill you are level 150 and you then can go kill all the bosses ( but the real way of getting coins faster is by using az of 46's mods).