The little island, named for its resemblance to the Rock of Gibraltar, was once owned by banker Jay Cooke, who built a 15-room, gothic-looking castle on it in 1865. It now holds Ohio State University’s Stone Laboratory, which studies freshwater ecosystems. Two-hour tours cover the castle, lab and other island sites such as Perry’s Lookout (a War of 1812 hot spot). Meet at the Boardwalk Restaurant dock at 341 Bayview Ave to catch the water taxi. No reservations.
Kayak the Bay also does guided tours to the island on Wednesday mornings.
