The Cottesloe Pylon is a Perth landmark: a concrete pylon built in 1936 as part of a failed attempt to erect a shark-proof net off Cottesloe Beach, later used for generations as a diving platform. It was heritage listed in 2003. When its spike toppled in a storm in 2009, it was rebuilt within five months with federal and Lotterywest funding, but deliberately angled and coated so it cannot be climbed, ending the era of jumping from it into water sometimes only a metre deep.

The pylon stands on shallow reef, and the area around it is a pleasant snorkel within the Cottesloe Reef Fish Habitat Protection Area. The limestone has low ledges and crevices covered in algae. Wrasse, old wives, stripeys, leatherjackets, bream and silver drummer gather around the structure, and rays and octopus are found on the reef and sand. The concrete itself has some encrusting growth.

Depths are only 1–4 m, so it is a snorkelling site rather than a scuba dive, and it lies in the surf zone, where surge and waves make it unpleasant on anything but flat days. Early mornings in summer and autumn with easterly winds give the calmest water and clearest visibility.

The pylon suits snorkellers and families who want a short swim to one of Perth's best-known structures. Divers seeking more should try Peters Pool to the north or the reefs at South Cottesloe.

Water temperatures on this coast range from about 17 °C in late winter to 22–23 °C in late summer, when the warm Leeuwin Current is strongest, so a 5 mm wetsuit suits summer and a 7 mm suit with a hood is more comfortable from June to October.

Park along Marine Parade, Cottesloe (paid, busy in summer), or take the train to Cottesloe station and walk 10 minutes to the beach. The pylon stands a short swim off the main beach, north of the groyne and near the Indiana tea house. Enter from the sand and swim out to the reef around the pylon.

The Cottesloe Surf Life Saving Club patrols the beach in summer; stay within patrolled areas when surf is running.

The pylon sits on shallow reef in the surf zone, so any westerly swell creates breaking waves and surge around it. Snorkel only on flat mornings with easterly winds and low swell, before the sea breeze. Winter storms bring large swell; the pylon's spike toppled in a 2009 storm.

Summer mornings are usually calmest.

Swim out from the beach, circle the reef around the base of the pylon in 1–4 m and explore the nearby ledges, then return to the beach.

No operator; a popular snorkel from the main beach.