Humpy Island is a small national park island just south of Great Keppel, and its southern side holds several fringing-reef dive sites that are sheltered from northerly winds. For that reason, it is one of the Keppel operator's most practical locations: when northerlies make the northern and western sites choppy, the boat heads to Humpy. The fringing reefs slope from the shoreline to sand at around 10-14 m.

Hard corals, including branching, plate and massive forms, dominate the upper slope, with soft corals and sponges deeper down. Visitors report turtles, sea snakes and a typical inshore mix of reef fish such as damsels, wrasse, parrotfish, rabbitfish and sweetlips, and rays on the sand. The dives are easy and shallow, suitable for new divers and for a series of dives over several days, since the southern shore offers a number of variations.

Divers who spent several days diving in the Keppels have reported doing three separate dives at Humpy Island, each at a different part of the southern side. Humpy Island's beach has a national park camping area, and the island is a popular stop for private boats. Its reefs are part of the Great Barrier Reef Marine Park, and some zones restrict fishing, so check the zoning map if you are boating independently.

It is a good site to combine with nearby Halfway Island for a relaxed two-dive morning.

Drive 40 km (about 40 minutes) from Rockhampton to Yeppoon, then 7 km south along the Scenic Highway to Keppel Bay Marina at Rosslyn Bay Harbour, where there is free and paid parking. Freedom Fast Cats and Keppel Konnections ferries run to Great Keppel Island (Fisherman's Beach) in about 30 minutes; Keppel Dive & Water Sports picks up certified divers from the island. Humpy Island lies just south of Great Keppel beyond Halfway Island, about 15 minutes by dive boat from Fisherman's Beach or 30 minutes by private boat from Rosslyn Bay.

Boats anchor off the southern side; the island's beach has a national park camping area (permit required) reached only by boat.

Keppel Bay is exposed to the prevailing south-east trades (strongest April-September) and to summer northerlies. The southern side of Humpy Island is protected from northerly winds, making it the Keppel operator's go-to area on northerly days (common on spring and summer afternoons). In strong south-easterlies it is exposed.

Currents are generally mild. Visibility 5-12 m, lower after rain.

Descend from the anchor to the sand edge at 10-12 m, follow the fringing reef along the island's southern shore with the reef on one side, and return shallower over the coral in 4-6 m, finishing with a safety stop near the boat.

Keppel Dive & Water Sports (PADI 5 Star, based on the Spit at Great Keppel Island next to Great Keppel Island Hideaway) runs guided boat dives to the Keppel sites most days, weather permitting, plus courses and Discover Scuba; site choice is made on the day according to wind. Private boats from Rosslyn Bay also dive here. Humpy Island's southern side is a regular choice when northerly winds blow.