The Bromby Islands lie north of the Gove Peninsula and are known to anglers as one of the best offshore fishing grounds from Nhulunbuy. For divers they offer two contrasting environments on either side of the islands, described by the Marine Life Network across a depth range of about 7–35 m.

The leeward side has easy, shallow coral reefs: hard coral gardens with plates, branching and massive corals, reef fish such as damselfish, butterflyfish, parrotfish and wrasse, and plenty of small invertebrates. It is an ideal first dive or snorkel in the trade-wind season, when the islands provide shelter.

The seaward side drops away starkly into deeper water. The wall is covered with soft corals, gorgonians, black corals and sea whips, and it is the place for bigger animals: turtles, reef sharks, manta rays and eagle rays are regularly seen, and whale sharks have been recorded. The combination of a vertical face, current and open water makes this one of the more dramatic dives in East Arnhem Land.

Visibility is usually good by Top End standards – the Gulf of Carpentaria's smaller tides and lower run-off give 10–20 m on good days – and the black corals and gorgonians on the wall are unusual this far west. The leeward gardens suit Open Water divers and snorkellers; the wall suits advanced divers comfortable with depth, current and drift diving. The islands are Yolŋu sea country; check permit requirements with Dhimurru and the Northern Land Council before landing. Because the islands double as a fishing hotspot, expect boats working the drop-off on good days and give trolling lines a wide berth when surfacing.

From Nhulunbuy launch at the Gove Boat Club ramp in Melville Bay and head north along the coast to the Bromby Islands, a longer run than Bremer Island that is best made early on a calm morning before the trade wind builds. The islands are also a popular offshore fishing destination, so local fishing charters know the way. Anchor in sand on the leeward side for the coral gardens, or drift the seaward wall with a following boat.

The Gove Peninsula sits at the north-west corner of the Gulf of Carpentaria, and tidal ranges here are much smaller than at Darwin (roughly 2–3 m), so diving is less tide-bound – but slack water still matters at channel and point sites. From April to September the south-east trade wind blows hard (often 15–25 knots), making the exposed east-facing coast and offshore islands rough by late morning; early starts and sites in the lee of islands are the norm. The build-up and early wet (October–December) bring glassy calm days and the best visibility.

In the wet season (December–March) the Gulf side is often still diveable, but inshore sites lose visibility after rain, cyclones are possible and box jellyfish are present.

For the wall: drop in on the seaward side at slack or the gentle part of the tide, descend to 20–25 m along the drop-off, drift or swim with the wall on one shoulder watching the blue for mantas and sharks, then ascend to the reef edge for the safety stop under an SMB. For the leeward gardens: anchor in sand and potter at 7–12 m.

Gove Diving & Fishing Charters (Nhulunbuy, ph 08 8987 3445) has provided air fills, gear hire, courses and boat trips to the offshore islands; confirm current operation before travelling. Otherwise private boats from the Gove Boat Club ramp, and local residents' informal dive groups.