The most-visited attraction in Maryland has more than 16,000 fish, sharks, dolphins, and amphibians dwelling in 2 million gallons of water. The Blacktip Reef exhibit mimics a coral reef in the Indo-Pacific waters. It features pufferfish, stingrays and more unusual creatures, such as the tasseled wobbegong, a carpet shark. The aquarium also features reptiles, birds, plants, and mammals in its rain-forest environment, inside a glass pyramid 64 feet high. The rain-forest ecosystem harbors two-toed sloths in calabash trees, parrots in the palms, iguanas on the ground, and red-bellied piranhas in a pool (a sign next to it reads "do not put hands in pool"). Each day in the Marine Mammal Pavilion, Atlantic bottlenose dolphins are part of several entertaining presentations that highlight their agility and intelligence. The aquarium's famed shark tank and Atlantic coral reef exhibits are spectacular; you can wind through an enormous glass enclosure on a spiral ramp while hammerheads and brightly hued tropical fish glide by. Hands-on exhibits include such docile sea creatures as horseshoe crabs and starfish. Arrive early to ensure admission, which is by timed intervals; by noon, the wait is often two to three hours, especially on weekends and holidays.