SS Thistlegorm

Overview & Historical Significance

The SS Thistlegorm is universally recognized by wreck diving authorities as the world’s premier shipwreck dive. Built in Sunderland, England, in 1940, the 128-metre (419-foot) British armed merchant vessel was sunk on 6 October 1941 at Sha’ab Ali in the Strait of Gubal after two Heinkel He 111 German bombers dropped two 2.5-tonne bombs directly onto Hold No. 4.

Discovered in the 1950s by Jacques-Yves Cousteau aboard the Calypso, the wreck rests upright on a flat sandy seabed at 30m to 32m, with the top deck structure rising to 16m to 18m.

Detailed Dive Route: The Standard 2-Dive Protocol

Because of the Thistlegorm’s massive scale and 30m depth, professional liveaboards and day charters operate a strict two-dive protocol.

Dive 1: Exterior Hull, Blast Zone & Steam Locomotives (24m–32m)

• Descent: Down the designated shot line directly to the bow or midships mooring point. Never let go of the line in open-water Gubal currents (often 1.5 to 2.5 knots).
• The Bow & Winches (16m–20m): Hovering over the massive anchor winches, pointing north.
• The Blast Crater (26m–30m): Swimming aft towards Hold 4, where the bomb detonated the munitions cargo. The hull is peeled outward like a tin can.
• The Propeller & Stern Guns (30m–32m): Rounding the upright 4.7-inch anti-aircraft gun and 3-inch machine gun mounted on the stern deck. Look under the counter-stern for the massive bronze propeller resting in the sand at 32m.
• The Locomotives: Blown 30 metres off the port side into the sand lies one of the Stanier 8F steam locomotives, complete with its coal tender.

Dive 2: Hold Penetration & WWII Cargo (18m–26m)

• Hold 1 & 2 (Upper Deck, 18m–22m): Entering the open cargo hatches with torches to reveal pristine Bedford trucks, Morris Commercial cars, aircraft wings, and crates of rifles.
• Hold 2 (Lower Deck, 22m–25m): Rows of classic BSA, Matchless, and Norton 16H military motorcycles stowed inside the truck beds.
• Hold 3: Crates of artillery shells, hand grenades, and portable mobile generators.

Gas Management & Nitrox Recommendation

• Mandatory Enriched Air (Nitrox 32%): Diving on standard Air (21% O2) gives an NDL (No-Decompression Limit) of only 20 minutes at 28m. On EANx32, your NDL extends to 35+ minutes, allowing complete hold exploration without decompression obligation. Maximum Operating Depth (MOD) on Nitrox 32% is 33.8m at 1.4 PPO2.
• Gas Turnaround: Turn the dive when the first diver reaches 100 bar or at NDL - 5 minutes.
• Ascent: Follow the permanent mooring line to 5m for a mandatory 3-to-5-minute safety stop.

Marine Life on the Wreck

The Thistlegorm functions as an artificial reef in the open strait:

• Giant green moray eels (Gymnothorax javanicus) living inside the engine cylinders.
• Resident schools of batfish, bluefin trevally hunting on the current-facing bow.
• Crocodilefish camouflaged on the rusted deck plating.

Marine Life & Habitat Zones (Biologically Verified)

• Apex & Pelagic Predators: Oceanic Whitetip Sharks (Carcharhinus longimanus), Scalloped Hammerheads (Sphyrna lewini), Giant Trevally (Caranx ignobilis).
• Reef Fish & Keystone Species: Masked Butterflyfish (Chaetodon semilarvatus), Red Sea Anemonefish (Amphiprion bicinctus), Napoleon Wrasse (Cheilinus undulatus).
• Macro Biodiversity & Benthic Invertebrates: Red Sea Crocodilefish (Papilloculiceps longiceps), Red Sea Frogfish, Pygmy Sweepers (Parapriacanthus ransonneti).
• Elasmobranchs & Marine Reptiles: Whitetip Reef Sharks (Triaenodon obesus), Giant Morays (Gymnothorax javanicus), Blue-Spotted Ribbontail Rays (Taeniura lymma).