Blowhole Reef consists of low sandstone reefs north of Blowhole Gully with numerous overhangs and swim-throughs in about 5 m. The Marine Life Network guide rates it 5 out of 10 and a good dive to finish a tiring week, with numerous types of fish darting around the ledges and the anchor of a small wooden vessel near shore. Access is by 4WD along the beach at low water only, or by boat. Its shallow, sheltered ledges make it a reasonable snorkel too.

King Island's reefs are best known to divers for their crayfish, which grow large in the cool, nutrient-rich Bass Strait water, and for sandstone and granite ledges covered in gorgonians, zoanthids and sponges. The Marine Life Network descriptions date from when King Island Dive Charters operated from Grassy; with no current operator, these sites are now visited only by divers who organise their own boat, and fishing pressure has reduced crayfish numbers since.

Recreational rock lobster and abalone fishing in Tasmanian waters needs a licence and is subject to seasons, size and bag limits. The east coast around Grassy is the reliable side of the island when westerly swell closes the west coast, and the island's lack of a chamber means aeromedical evacuation for any diving injury, so conservative dives are the rule.

This is a site for self-sufficient visiting divers with their own boat and a local contact; there is no one on the island currently guiding dives here, and the position given is an estimate from the published description.

King Island is reached by air from Melbourne (about 50 minutes), Burnie/Wynyard or Launceston; there is no passenger ferry, so divers fly in and hire a vehicle at the airport near Currie. Currie, the main town, is on the west coast; Grassy (with its harbour and boat ramp) is on the south-east coast about 30 minutes' drive away. Roads to the coast are a mix of sealed and gravel.

Blowhole Reef is reached by 4WD along the beach at low water only, or by boat from Grassy (about 15 minutes).

King Island sits in the path of the Roaring Forties, and its west coast (Currie, Netherby, Cataraqui, Brahmin) takes the full force of the prevailing westerly and south-westerly swell; these sites are diveable only after long calm periods or in easterly weather, which is most common in late summer. The east coast around Grassy is sheltered in westerlies and becomes the fallback. Strong tidal streams run around the island's capes after gales.

Shore access only at low water.

Explore the low sandstone ledges and swim-throughs at about 5 m and look for the small wooden vessel's anchor near shore. Turn the dive at half gas (thirds where current or overhead sections are involved), deploy an SMB before surfacing for the live-boat pick-up, and complete a 3-minute safety stop at about 5 m where depth allows.

No dive shop or charter currently listed on King Island (Underwater Australasia has no listings); the King Island Dive Charters/Dive Centre referred to in older guides no longer appears to trade. Visitors must bring their own gear and arrange cylinders and a boat locally (hire weights/tanks on the island where possible to reduce air freight). Verify any current operator before travelling.