The 10 Metre Spire is one of the offshore West End sites that make Rottnest's far end so highly regarded by experienced Perth divers. Marinelife.org.au places it about a mile south of the West End, with the reef top at about 10 m and an average depth of 18 m, dropping to 27 m. It describes plenty of big overhangs, a large cave on the northern side that is often packed with fish, and hard and soft corals.

The spire concentrates fish in the way offshore pinnacles do. The cave and overhangs hold schools of bullseyes and old wives, while the open water around the spire can bring buffalo bream, western blue groper, dhufish and samson fish, and pelagic species when current is running. The West End Demersal Sanctuary Zone protects bottom-dwelling species across this end of the island, so demersal fish are relatively abundant.

The dive's reputation is tempered by its conditions: it needs less than 1 m of swell and very little wind, is prone to strong currents, and is a long way from help. That makes it a dive for Advanced divers with good current skills, nitrox and a well-organised boat with a pickup driver. When it all lines up, it is one of the best reef dives off Perth.

Published detail beyond the marinelife.org.au listing is scarce, so seek local knowledge before planning, and have a sheltered backup such as Roe Reef in mind for the day. A good skipper who can follow bubbles in current is essential for this site.

A West End site about 30 km from Fremantle - 1.5 hours or more by boat. Only attempt from a capable boat on a calm, low-swell day; locate the spire by GPS and sounder and live-boat or anchor off the reef. Rottnest lies about 18 km west of Fremantle; allow 45-90 minutes each way by charter or trailer boat depending on the site.

Follow Rottnest Island Authority mooring and anchoring rules - do not anchor on reef or in sanctuary zones - carry a marine radio and log a trip plan, as the crossing of Gage Roads can turn rough when the afternoon sea breeze arrives.

Needs very calm weather - marinelife.org.au specifies swell under 1 m and minimal wind - and is prone to strong currents. Best at neap tides on summer or autumn mornings with light easterlies. General pattern at Rottnest: summer brings calm morning easterlies followed by a strong south-westerly sea breeze from late morning, so dive early; winter brings north-westerly fronts and large swell, with clear, calm spells between them.

Check the Bureau of Meteorology coastal forecast for swell height and period before committing.

Descend onto the spire top at 10 m, spiral down its flanks past the overhangs to the large northern cave at around 18-20 m, then return up the spire and ascend on a DSMB, allowing for current. Agree a turn pressure before descending (half gas, or a third where current is likely), carry a DSMB, and make a 3-minute safety stop at 5 m.

Nitrox recommended; live-boat pickup and DSMBs essential.

No regular operator - private boats and dive clubs (e.g. UWA Underwater Club) only. Nearest dive services: Perth Scuba, Bucket List Diver and Dolphin Scuba (Perth/Fremantle) run Rottnest boat trips; there are no dive shops or air fills on the island.