Big Tunnels

Big Tunnels is a Grand Cayman West Wall dive site celebrated for its dramatic coral-arch swim-throughs that pierce the reef shelf at the wall lip. The site begins on a reef plateau in roughly 15 metres and descends through a sequence of high-roofed tunnels and arches in 21 to 27 metres, formed where ancient coral overgrowth has bridged narrow canyons in the limestone shelf. The arches are wrapped in giant barrel sponges, orange elephant-ear sponges, deepwater sea fans, black coral and sheet corals, and shafts of sunlight cut through gaps in the ceilings. Beyond the tunnels, the wall plunges vertically thousands of metres into deep blue. Resident wildlife includes Caribbean reef sharks patrolling the drop-off, eagle rays gliding the wall edge, hawksbill turtles, southern stingrays in the sand patches between coral heads, schools of horse-eye jacks, queen and French angelfish, midnight parrotfish, and large green moray eels in the tunnel walls. Visibility along the West Wall commonly exceeds 30 metres in the dry season from December to May. The depth and tunnel navigation rate the dive advanced.