Sylph's Hole is one of the island's best-known shore snorkel sites and a designated sanctuary zone. The NSW marine park authority names it, with North Bay, as a site reached by a short swim from shore, and the island's pocket guide lists McCulloch's anemonefish, coral and turtles here and marks it as a sanctuary zone. It is at the northern end of the lagoon, off Old Settlement Beach, which is itself known for turtles.

The attraction is the combination of easy access and good marine life. Green turtles graze in the area and are often seen by snorkellers, while the coral holds McCulloch's anemonefish – an endemic found only around Lord Howe and nearby reefs – along with the lagoon's usual mix of reef fish. The water is shallow and generally calm, sheltered by the barrier reef from the open ocean.

The pocket guide and marine park materials recommend checking conditions and the tide before snorkelling. Mid to high tide gives more water over the coral and makes the swim easier; at low tide the lagoon floor is very shallow and it is easy to damage coral. Footwear helps when wading because of sea urchins and reef shells.

It is suitable for snorkellers of all abilities in calm conditions, including families. There is no need for a boat or guide, though the snorkel tour operators include it on some trips. As a sanctuary zone, fishing and collecting are prohibited. Depth figures here are estimates; the hole itself has not been described in detail by any source found.

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. Sylph's Hole is at the northern end of the lagoon off Old Settlement Beach.

Ride or walk north along Lagoon Road and Neds Beach Road towards the airport end of the settlement and take the short track to Old Settlement Beach; bikes can be left at the beach. Snorkel gear can be hired at the Lagoon Road boatsheds. The hole is a short swim from shore – ask locally for the exact entry point.

Sylph's Hole is inside the lagoon near its northern end and is sheltered by the barrier reef in most weather. Strong westerlies and north-westerlies make it choppy and stir the sand; northerlies can push swell towards the northern lagoon. Snorkel at mid to high tide – at low tide the coral is close to the surface and the swim is harder.

Visibility is usually 10–20 m. Best from November to April for warm water; there is no stinger season.

Enter from the beach at mid to high tide and swim out to the hole, snorkelling slowly over the coral and watching for turtles. Stay clear of the reef edge and return to the beach before the tide drops.

No operator needed – independent shore snorkel. Snorkel gear hire from the Lagoon Road boatsheds; some snorkel tours include the northern lagoon.