South Mandu is one of the quieter Cape Range snorkels, a shallow, sheltered coral garden close to shore south of Turquoise Bay, reached by a 500 m walk from the car park. Guides describe it as snorkellable only at high tide because the coral lies in very shallow water.

The coral gardens are mostly branching and plate corals interspersed with sand and rubble, with typical lagoon fish — damsels, parrotfish, wrasse, butterflyfish — and the chance of turtles, rays and small reef sharks. Its relative remoteness keeps crowds lower than at Turquoise Bay or Oyster Stacks.

The name comes from nearby Mandu Mandu Gorge; offshore on the outer reef lies Mandu Wall, a boat dive visited from Tantabiddi. South Mandu itself suits beginners and families on calm high-tide days.

Lagoon corals here were exposed to the 2025 heatwave and some bleaching or mortality is likely.

Planning a Cape Range day: the national park's lagoon sites stretch about 50 km along Yardie Creek Road from Tantabiddi to Osprey and Sandy Bay, all within the World Heritage-listed Ningaloo Coast. The reef crest sits a few hundred metres to a couple of kilometres offshore, enclosing a lagoon of sand, seagrass and coral bommies, and a series of sanctuary zones (look but don't take) protect the best-known snorkel areas. There are no shops, fuel or air fills in the park, so bring water, food, sun protection and reef shoes from Exmouth. The Milyering Discovery Centre has current information on conditions and zones. Mornings are usually calmer, clearer and cooler than afternoons, and checking the tide chart is essential for the shallower sites.

Drive into Cape Range National Park via Yardie Creek Road (park fee), about 70 km from Exmouth, to the South Mandu car park south of Turquoise Bay. Walk about 500 m along the beach to the snorkel area and enter from the sand. The coral is in shallow water close to shore; go on a high tide.

Bring water and shade – there are no facilities at the beach beyond the car park, and the park has no shops or fuel.

Cape Range lagoon sites are protected by the reef crest, but a south-westerly swell pumps water over the reef and out through the gaps, strengthening currents in the lagoon, particularly on a high tide and big swell. The afternoon south to south-westerly sea breeze (often 15–25 knots from spring to autumn) makes the water choppy and reduces visibility, so mornings are best. Summer air temperatures exceed 40 °C; cyclone season is November–April.

Irukandji and other stinging jellyfish occur mainly in the warmer months and autumn. Visibility in the lagoon is usually 5–15 m.

Snorkel site. Walk to the coral area, enter at high tide and float over the coral gardens parallel to the beach, returning the same way.

Independent shore snorkel; no operator needed. Exmouth dive shops hire snorkel gear and some tour companies include lagoon snorkels on Cape Range day trips.