At any point in the game go to the 1st dungeon. Go to the bosses room. Fall over the side and hold up and repeatedly swing your sword. Make your way to the botom edge of the window, go to the right edge of the window, then all the way up. You will be in the angler dungeon. Open chests to get the items. You will only get two of them. Find the mini boss and beat it. Save and find the flipers.