Thunder Point is the western bookend of the Merri Marine Sanctuary and the most dramatic piece of coast in Warrnambool, a headland of limestone cliffs and stacks where the Southern Ocean swell explodes with the noise that gives it its name. The sanctuary boundary runs along the point, so the reef immediately off it is protected while the water to the west, toward Eagle Rock and Shelly Beach, is open and, in the Scuba Doctor's words, renowned as a great site for catching abalone and crayfish. Divers need to know where the line is before taking anything. Underwater the seafloor is exposed and rugged: from about 5 m at the shore the bottom slopes gently across rock formations that give way to isolated reefs surrounded by sand in 15–20 m around 150 m offshore. The reefs carry kelp and heavy invertebrate growth, ledges with crayfish and abalone, and the sanctuary's fish and sharks – wrasse, magpie perch, sweep, boarfish, Port Jackson sharks, wobbegongs and rays – with fur seals and dolphins regular and little penguins from Middle Island hunting over the reef. Visit Victoria describes the scenery at Thunder Point and Pickering Point as breathtaking.

It is the hardest of the Warrnambool shore dives. The entry is a scramble down a cliff onto a platform that takes the full swell, the site faces south-west with nothing between it and Antarctica, and it is diveable only in excellent conditions with minimal swell. The Scuba Doctor's advice to look at the water first and go home if there is lots of white water applies more here than anywhere. Boat divers from the Lady Bay ramp can dive the outer reefs without the cliff scramble and with an easier exit. For an experienced diver on a flat autumn day the point offers the deepest and wildest reef in the sanctuary a few minutes from town, and it is a fine place to sit above the water and watch the swell when it is not.

From the centre of Warrnambool follow Merri Street west, then MacDonald Street south to its end at the Thunder Point Coastal Reserve, about 3 km; the car park is on the right (west) at the end of MacDonald Street, with a second, southern car park at the lookout. From the southern car park scramble down the south-western side of the cliff to the rock platform – a steep, awkward carry that needs care with gear. Enter from the platform between sets.

Boats from the Lady Bay ramp 2 km east reach the outer reefs in ten minutes. Warrnambool Diving on Fairy Street is 3 km away.

The Merri Marine Sanctuary sites face south-west into the Southern Ocean and are, in the Scuba Doctor's words, prone to surge and swell, with conditions able to change quickly into dangerously rough seas with big swells and strong currents. Dive at low tide with a low swell (under about 1 m at Stingray Bay, under 0.5 m for the exposed sites) and light offshore northerly to north-easterly winds; any onshore southerly through westerly wind makes the sites treacherous. Check the water from the car park – if you see lots of white water, head home.

Visibility is best after settled northerly weather in autumn and poor after rain from the Merri River. Warm-water upwelling is absent; the Bonney Upwelling can bring cold green water in summer. Thunder Point is the most exposed of the group, named for the sound of the swell on its cliffs, and the Scuba Doctor rates it diveable only in excellent conditions with minimal swell and light northerly winds – the first site to close out and the last to reopen.

Enter from the platform on the south-western side, descend in 5 m and follow the gently sloping bottom seaward across the rock formations to the isolated reefs surrounded by sand in 15–20 m about 150 m out. Explore the reefs and their ledges, turn at half gas, return on a reciprocal bearing up the slope to the point and exit at the platform, timing it between sets.

Warrnambool Diving (Fairy Street) – air fills, PADI courses, divemaster-led local shore dives on request; Daktari Surf & Dive (Warrnambool) – snorkel gear and guided snorkels; Warrnambool dive club members dive the sanctuary regularly on calm days. Thunder Point is also a popular abalone and crayfish spot for local divers, outside the sanctuary boundary.