When you see the sun in the middle of the top screen, the tides will change allowing you to go to the hidden beach at the right side of the beach area. You only have about 2 hours in the game to get back out of the hidden beach, if you spend too much time on the beach, the tides will lock you in until the sun rises up. The beach contains 4 green bamboos, 4 scallops and 3 bamboo shoots.