Every year, the National Aquarium takes its favorite Halloween tradition underwater. This October 31st, Aquarium divers will take a plunge in the Blacktip Reef exhibit and carve pumpkins underwater. Divers will host two underwater pumpkin-carving sessions. Carvings will begin promptly at 10 a.m. and 2 p.m. The underwater pumpkin carving is included with the price of admission.