Montague Island (Barunguba) lies about 9 km off Narooma and is home to the largest fur seal colony in NSW. Australian and New Zealand fur seals haul out on the rocks at the northern end, and Narooma Charters reports up to 1,800 seals in the cooler months and 200–500 in summer. A ScubaBoard report notes that the colony consists largely of adult males, so there are few pups. The Marine Life Network lists the Seal Colony on the north-east side at around 10 m, with as many as 500 seals at peak times, and McFadyen describes diving in Pebbly Bay, where you do not need to go deeper than 9 m.

The dive is about the seals. They are clumsy on land but fast and acrobatic underwater, spiralling around divers, blowing bubbles and nibbling fins. McFadyen suggests sitting on the bottom and watching, or doing barrel rolls to catch their attention; young seals will come within centimetres. The bottom is boulders and kelp with the usual reef fish – blue groper, sweep, yellowtail, leatherjackets – but most divers barely notice them.

The seal dive suits divers of all levels, including Open Water divers and snorkellers. Seals are wild animals: do not touch or feed them, give way when they approach, and avoid getting between a seal and its escape route. September and October are traditionally the best months, although seals are present year-round. The trip across the Narooma bar and 25 minutes of open sea can be rough, so seasickness tablets are worth taking. Most trips combine a seal dive with a reef or grey nurse dive elsewhere around the island.

Boat access only. Narooma Charters leaves from the Narooma town wharf on Wagonga Inlet (about 25 minutes to the island) and Underwater Safaris from Narooma marina; private boats launch at the Apex Park or Bar Beach ramps inside the inlet. Every trip crosses the Narooma bar, one of the most dangerous on the NSW coast, so departures depend on bar conditions; Bermagui harbour (about 24 km by sea) is the fallback launch point.

The seals haul out on the northern end of the island; operators choose the most sheltered bay on the day (Pebbly Bay in McFadyen's account) and anchor or drift in 5–10 m.

Montague Island is about 9 km offshore and fully exposed, but with sites on all sides operators can usually find shelter from the wind of the day: the northern bays in southerlies, the western side in easterlies. The real limit is the Narooma bar, which closes in moderate easterly or southerly swell, especially on a run-out tide; McFadyen calls it probably the most dangerous bar in NSW. Trips are frequently delayed or cancelled, so allow spare days.

Currents are strong on the northern and eastern sides. The seal bays themselves are shallow and surge in swell, so operators pick the lee side. September and October are traditionally the best months for seal interaction.

Descend to the boulder bottom in 5–9 m and stay low and still near the seals' playground rather than chasing them. Seals approach curious divers who roll and twist. After the seals, explore the boulders for fish and invertebrates and return to the boat.

Underwater Safaris (Narooma) runs seal dives year-round (5–20 m, age 12+) and snorkels; Narooma Charters runs single and double dives from the town wharf at 8 am (4 hours, 25-minute ride) and seal snorkels. Sydney shops (Abyss, Frog Dive, Dive Centre Bondi, Dive Centre Manly) run weekend trips using these boats.