Sanibel Island and Captiva Island have different amenities, but they also have a lot in common. The two sister islands are connected by Sanibel-Captiva Road. The Blind Pass Bridge crosses over the channel that sometimes separates the two islands.

Sanibel and Captiva islands are separated by a narrow, dynamic body of water known as Blind Pass. This pass is a natural (though often man-managed) strait that allows water to flow between the Gulf of Mexico and Pine Island Sound. Travelers move between the two islands via the Blind Pass Bridge, a short span that offers spectacular views of the turquoise water. Blind Pass is world-famous among "shellers" because the currents frequently deposit vast quantities of unique seashells on the surrounding sand, particularly on the Sanibel side. However, the currents at the mouth of the pass are notoriously strong and dangerous, so while wading and shelling are popular, swimming is generally discouraged. Historically, the two islands have been connected and disconnected multiple times by major hurricanes, such as the 1921 storm that carved out the pass as it exists today, highlighting the ever-changing nature of Florida's barrier island geography.