Nine Mile Reef is an offshore Tweed Heads reef for experienced boat divers who want rugged structure, sharks, and a real drift window instead of a mellow shore-style reef. The ride runs over a coral ridge with ledges, gutters, and bommies, where current and cleaner-water windows shape the dive as much as the reef itself. On the right day it delivers shark, ray, and turtle sightings without pretending to be a sheltered beginner site.