Erscott's Blind is a lagoon dive with a difference: it is deep enough for a proper scuba dive and holds a group of resident Galapagos sharks. Michael McFadyen describes a bowl-shaped formation within the coral reef, about 125 m north-west to south-east and 75 m across, just inside Erscott's Passage – the first southern entrance to the lagoon. It is about a kilometre from shore near Capella Lodge and 400 m from the centre of the passage.

The centre of the bowl is 18–20 m deep; the edges are about 7 m on the western side and 15 m on the east. The coral walls rise about 3 m from the sand, and the site deepens to 14–16 m along the eastern section. The usual route is a clockwise circuit from the western edge, heading north around the perimeter before returning across the centre.

The Galapagos sharks are the highlight – McFadyen saw six, and describes them as very friendly – and the lagoon's coral and reef fish make up the rest of the dive. Spanish dancers and Halgerda nudibranchs, several species of butterflyfish, humphead wrasse and damselfish are all recorded.

Because of the fine sand, visibility is lower than outside the reef; McFadyen had about 10 m in May, with water at 21.7°C. That is the trade-off for a site that can be dived in almost any weather. It suits Open Water divers and makes a good second dive or bad-weather option. Proximity to Erscott's Passage means tidal flow can be felt at times.

Lord Howe is reached only by air: QantasLink flies from Sydney daily (about 1 h 50 min), with Brisbane and seasonal Port Macquarie services. Accommodation must be booked before flights (visitor numbers are capped at about 400) and the checked-baggage limit is 14 kg, so most divers hire gear on the island. The lagoon sites are reached from the Lagoon Road boatsheds: Dive Lord Howe's boat is moored in the lagoon and reaches the holes in about 5 minutes, and glass-bottom and snorkel boats (Islander Cruises, Marine Adventures, Lord Howe Environmental Tours and others) run daily trips.

Snorkellers can also hire kayaks at the boatsheds, but the holes are well offshore near the barrier reef, so a guided boat is the practical option.

The lagoon is protected by the fringing barrier reef on the island's western side and is diveable in almost all weather, which is why operators use it when the outer reef is closed. Strong westerly and south-westerly winds – mainly with winter fronts – make it choppy and push swell over the reef, stirring the sand and cutting visibility. The holes are deep enough to dive at any tide, but the surrounding lagoon floor is very shallow at low tide and boats time runs accordingly.

Visibility is usually around 10–20 m (lower than outside the reef), and water is warmest from January to April.

Enter at the western edge of the bowl and swim clockwise, heading north along the reef perimeter and looking under the coral edges for Galapagos sharks resting on the sand. Complete the circuit, then cross back over the centre of the bowl (18–20 m) to finish at the western edge.

Dive Lord Howe – lagoon dives used daily as a sheltered option and for courses; snorkel and glass-bottom boat tours by Islander Cruises (daily access to the southern and northern sanctuaries), Marine Adventures, Lord Howe Environmental Tours, Reef N Beyond and Liv For The Sea.