The Danger Marks site takes its name from the isolated danger navigation markers on the Orpheus Island side of the Orpheus–Pelorus channel, which warn boats off the shallow reef that the North Queensland Underwater Explorers Club dives. The club locates the site by the markers and a reference boulder on the Orpheus shoreline. It is a shallow dive, with a minimum of about 5 m, on a rock base cut into gutters with strikingly symmetrical walls, carpeted by low-lying, colourful corals.

The gutters are the feature: they channel water and fish and give the reef an orderly, corridor-like structure. The club lists juvenile red emperor, coral trout, wrasse, parrotfish and sweetlips, and the Marine National Park zoning on the Orpheus side means fish are protected and relatively approachable. Navigation can be confusing in the similar-looking gutters, so the club recommends swimming a large box pattern with 90-degree compass turns, returning to the anchor.

Current in the channel can affect the site on running tides; slack water is the best time. The Danger Marks make a good shallow second dive after the deeper Ray's Lump or Western Edge, or a site for less experienced divers in the group. Like all Palm Island sites, there is no regular operator and no infrastructure, and visibility of 6–12 m is typical.

Documentation is limited to the club's page, and the exact position is not published, so confidence is modest. Skippers should also remember that the marks exist because the reef is a hazard to boats: approach slowly, keep a lookout for bommies near the surface at low tide and anchor well clear on sand, leaving someone aboard while divers are down.

Boat only. The Palm Island group lies 20–25 km off the coast between Townsville and Ingham. The quickest access is from the Lucinda or Dungeness boat ramps near Ingham (about 1 hour 20 minutes' drive north of Townsville via the Bruce Highway), from which a small boat reaches Orpheus and Pelorus in about 30–45 minutes across Halifax Bay; Taylors Beach ramp is an alternative.

From Townsville the run is roughly 1.5–2 hours. Orpheus Island Lodge guests arrive by helicopter or seaplane and dive from the lodge's boats. Campers on Orpheus (QPWS permit) and Pelorus (self-sufficient, Hinchinbrook Shire Council) usually arrive by private boat or water taxi.

Use public moorings where available and check no-anchoring areas. Locate the isolated danger navigation marks on the Orpheus side of the channel and a reference boulder on the Orpheus shoreline; anchor on sand clear of the marks (Marine National Park – no fishing; check no-anchoring areas).

The Palms are high continental islands, so some shore always offers a lee, but the Orpheus–Pelorus channel and exposed points are hit by the south-east trades (15–25 knots, April–September) and by strong tidal streams – springs can produce currents that make the points undiveable except at slack water. Visibility is typically 6–10 m and reaches 15 m in the winter channel; it falls after strong winds and during the wet season (January–April) when the Herbert River floods discolour the water. The calmest, clearest conditions come in the October–December build-up.

Marine stinger season (box jellyfish and Irukandji) runs roughly November to May – wear a full-length stinger suit or wetsuit with hood and gloves, carry vinegar. Cyclone season November–April; tropical lows and cyclones can close sites and damage coral (TC Yasi 2011, TC Debbie 2017).

NQUEC suggests navigating a large box pattern with 90° compass turns across the gutters at 5–8 m, returning to the anchor. Keep an eye on current and surface near the boat.

Orpheus Island Lodge – private dive charters for guests to local reefs (minutes away) and the outer reef (~75 min), plus Discover Scuba shore dives; otherwise private boats from Lucinda/Taylors Beach, campers and NQUEC club trips. No scheduled public dive trips.