Griffiths Island is the low basalt island that shelters the mouth of the Moyne River at Port Fairy, joined to the town by a causeway and crowned by the 1859 lighthouse. Offshore from it, the Scuba Doctor describes an extensive network of boulder reefs and ridges extending into Port Fairy Bay: rocky reef with ledges, gutters and bommies on a sandy bottom, dropping from 5 m near shore to about 15 m some 80–100 m out and to 20–30 m further offshore. The boat dives on the shallow reefs are, in the same source's words, some of the best in the region, and the diversity of marine life about 500 m offshore in 20 m is described as high. The basalt is heavily encrusted – sponges, ascidians, bryozoans and hydroids on the shaded faces, kelp and mixed algae on the tops – and the ledges hold southern rock lobster, abalone and the invertebrate life that makes the site good for macro photography. Fish include blue-throat and senator wrasse, magpie perch, sea sweep, herring cale, zebrafish, boarfish and leatherjackets, with Port Jackson sharks, wobbegongs and rays on the sand, cuttlefish in the gutters and fur seals from Lady Julia Percy Island, 15 km to the west, passing through. Short-tailed shearwaters nest on the island in tens of thousands from September to April.

For non-divers and families the island offers two snorkels: South Mole Beach, a 200 m beach beside the river entrance with small waves, and Griffiths Island Beach, a pocket in the lee of the reef where a calm lagoon forms at low tide. For divers with a boat the reefs are the best natural diving between Warrnambool and Portland and a short run from the town ramp, with the added interest of the Port Fairy lighthouse and, on the way out, the harbour training walls. No dive charter operates from Port Fairy, so the site is used by Warrnambool Diving on occasion, by fishing charters by arrangement and by private boats. It suits Open Water divers with a boat on a settled autumn day, and the shallow ridges near the island make a forgiving second dive or a snorkel on the calmest days.

Port Fairy is 28 km west of Warrnambool. Boats launch at the Griffiths Street ramp on the Moyne River in town and run out through the training walls; the reefs begin immediately outside the river mouth and the main dive area off the lighthouse is 1–2 km away, five to ten minutes. Anchor on sand between the ridges.

For snorkelling, walk the causeway to Griffiths Island from the end of Griffiths Street (about 1 km) to Griffiths Island Beach, a small beach in the lee of the reef with a calm lagoon at low tide, or use South Mole Beach beside the river entrance. Warrnambool Diving supplies air; Port Fairy has none.

Best dived in good conditions with a low swell and light westerly to northerly winds. The reefs face south and south-east into the Southern Ocean and take swell from the south-west around the island, so boat diving is comfortable under about 1 m; south-easterly and easterly winds bring sea straight onto the site and into the river entrance, which can be dangerous to cross in a small boat on an ebb tide against a swell. Visibility is best after settled weather in autumn and drops after rain from the Moyne.

The Griffiths Island lagoon snorkel is a low-tide activity in small swell; South Mole Beach averages half-metre waves. Shearwaters nest on the island September–April.

Anchor on sand between ridges in 12–15 m off the lighthouse, descend and work along the boulder ridges and bommies, checking the ledges and gutters for crayfish and the sand edges for rays. Continue seaward toward 20 m if visibility is good, turn at half gas, return to the anchor and ascend the line with a 3-minute stop. The shallow ridges at 5–10 m near the island make an easy second dive.

No dedicated dive charter in Port Fairy. Warrnambool Diving runs occasional boat dives; Port Fairy fishing charters will take divers by arrangement; local club divers use private boats. Snorkelling from the island is independent.