Ile des Phoques - the island of seals - is a small granite island rising steeply from the sea between Maria and Schouten islands, and it is regarded as one of the best dives in Tasmania. The Marine Life Network guide rates it 10 out of 10, and Discover Tasmania and the Spirit of Tasmania guide single it out as one of the state's most exciting dives, among fur seals and sea caves.

The seal colony on the south-west side is the main attraction. Hundreds of Australian fur seals now use the island, and in the water at around 20 m the younger animals swirl around divers, mouthing fins and blowing bubbles. The second highlight is a cave system that passes through the north-west corner of the island, well lit and emerging on the eastern side; the TSDC describes dramatic caves, large swim-throughs and towering rock formations. Walls around the island carry sponges, sea whips and colourful invertebrates, and reef fish are plentiful.

Depths are typically 15-25 m, with deeper water off the walls. The island is small enough that the skipper can move divers to the most sheltered face, but it is still an exposed offshore site, and the boat run from Triabunna takes the best part of an hour.

Ile des Phoques suits Advanced Open Water divers comfortable with open-ocean boat diving, swim-throughs and the unpredictability of large seals. It is a seasonal highlight for Hobart dive shops and clubs whenever a calm weather window allows the trip.

Ile des Phoques lies about 8 km off the coast north-east of Maria Island. Most trips leave from the Triabunna ramp (about 45-60 minutes by fast boat), or from Swansea or Coles Bay. Hobart operators such as Go Dive Tasmania have run day trips, trailering boats to Triabunna.

The island is steep-sided with no landing, so the boat live-drops divers on the lee side. Allow a full day including the drive from Hobart (1 hr 15 min to Triabunna).

Maria Island's western and northern shores (Darlington, Fossil Cliffs, Painted Cliffs) are sheltered from easterly ocean swell but exposed to strong westerlies and north-westerlies blowing across Mercury Passage, which are common in winter and spring. The eastern side (Mistaken Cape, Bunker Bay) faces the open Tasman Sea and needs westerly weather and small swell. Southerly swell wraps around Cape Peron and the southern end.

Visibility drops after rain as runoff flows from the Prosser River into Mercury Passage. Ile des Phoques is fully exposed in the open Tasman Sea; the long run from Triabunna requires a settled forecast with swell under about 1.5 m. Divers choose the lee side on the day.

Seal pupping in late spring-summer increases the chance of large sharks around the colony.

Drop on the south-west side near the seal colony at about 20 m and spend time with the seals, then move to the north-west corner and swim the well-lit cave system through the island, exiting on the east side if conditions allow. Ascend along the island's wall.

No operator based on Maria Island. Hobart shops run occasional trips: Go Dive Tasmania has offered Ile des Phoques seal dives and filmed Troy D dives; Tasmanian Scuba Diving Club and Tas Uni Dive Club run club trips from Triabunna. Most diving is from private boats.