Challenger Bay is best known for one of the most dramatic night dives on the Great Barrier Reef. Located between Ribbon Reefs No. 9 and 10, it is a sheltered bay where liveaboards commonly spend the night, and the resident predators have learnt to use divers' torches for hunting. Giant trevally and schools of red bass shadow divers after dark and dart into the beam to snatch small fish, which makes for an adrenalin-charged experience that Mike Ball's guides describe as fish actively hunting in the dive lights.

By day the site is gentler. The reef platform sits at about 5 m and slopes to a sandy bottom at 20–30 m, with hard coral fields, sandy gullies and scattered bommies. Dive the World describes it as hard coral fields with sandy gullies, multiple bommies and a main reef wall. The shallows took a hammering from the 2014–15 cyclones, but the hard corals are recovering, and the sand holds garden eels, stingrays and whitetip reef sharks.

Fish life is abundant: batfish, diagonal-banded sweetlips, mackerel, barracuda, clown triggerfish, pufferfish and giant moray eels, with giant clams scattered through the coral. Challenger Bay sits beside Gotham City and Mike Ball treats the two as neighbours; the same predators patrol both.

Because the mooring is shallow, sheltered and right under the boat, it suits every level of diver and is often the first night dive for people new to it. Keep a firm grip on your torch and your nerves; the fish move fast and close, but they are interested only in their prey.

Liveaboard only (or fly-dive via Lizard Island). Mike Ball Dive Expeditions' Spoilsport and Spirit of Freedom depart Cairns (Trinity Wharf / Marlin Marina) in the evening and steam north overnight, roughly 12–14 hours and 200–250 km, to reach the Ribbon Reefs by morning; some itineraries fly Cairns–Lizard Island (about one hour, scenic flight along the coast) and board or disembark there. Trips run 3–7 nights and include Challenger Bay as an afternoon and night-dive mooring.

Divers enter by giant stride from the dive deck at the mooring and descend the mooring line. Because it is sheltered, liveaboards often spend the night here, so it is dived in the late afternoon and again after dark straight off the back of the boat.

The Ribbon Reefs sit on the edge of the continental shelf and take the full south-east trade wind from April to October. Lagoon-side moorings stay diveable in 20–25 knot SE winds, but reef-front sites and passes need lighter winds; liveaboards shelter behind the reefs overnight. September to December is usually calmest.

Tidal flow through the gaps between the Ribbons is strong on springs, so exposed pinnacles are timed for slack water. December to April brings rain, lower visibility and cyclone risk; box jellyfish and Irukandji are possible November to May. Challenger Bay is one of the most sheltered moorings on the Ribbons and is diveable in all but the strongest trades, which is why it is used as an overnight anchorage.

By day, descend the mooring to the sand at 15–20 m, visit the nearest bommies and the base of the main reef wall, then return over the hard-coral fields to the 5 m reef platform. At night, stay close to the boat, keep torches pointed down and let the hunting trevally and red bass work around you.

Mike Ball Dive Expeditions (Spoilsport) – Ribbon Reef and Coral Sea itineraries from Cairns, several departures a month; Spirit of Freedom – 3-, 4- and 7-night trips from Cairns/Lizard Island, weekly. Usually scheduled as the night dive.