The scenario—your nose bumping the Great Barrier Reef—implies you're underwater, on the reef itself. That means:
Australia—specifically, the Great Barrier Reef Marine Park off the coast of Queensland, stretching 2,300 km from Bundaberg to the Torres Strait. Major access points: Cairns, Port Douglas, Airlie Beach (Whitsundays), Townsville.
Look, don't touch. Coral is a living animal; oils, bacteria, and physical contact damage polyps, spread disease, and remove protective mucus. Many reef zones are no-touch/no-take. Fines apply. Be a guest, not a threat.