The zig-zag path is steep but soft underfoot with a cushion of leaf litter dappled by tropical sunlight penetrating the forest canopy. It ends abruptly at a jagged coral outcrop where rough stone steps lead up to a cave with a low ceiling.
A jumble of 100 human skulls fills the dark interior, blending in with the ghostly white limestone of the cave. Their dark eye sockets stare out at the living world of the jungle as if they are a silent group of startled people huddled behind the rock-bound cave entrance.
The desiccated craniums are coated with green algae, giving the skulls the appearance of zombie heads from a horror movie.
The cave is a graphic statement about the everlasting human cycle of life, death and rebirth. These Doini Island ancestors once fought bitter battles with neighbouring tribes. Missionaries brought more peaceful times.
Today, 30 Melanesians live on the island, working for the Doini Island Plantation Resort. The bitter tribal warfare is behind them and this island at the eastern tip of Papua New Guinea is a haven of peace and tranquillity, dubbed by the owners as "The Island of Love".
I set out on the skull cave walk with a group of travellers early in the day, following a 4WD track that circles most of the 1sq km island. It takes around four hours to circumnavigate the island on foot, visiting the airstrip, the cave, Love Beach and the Rock Pool.
A steep hill has to be negotiated beyond the cave, which is the halfway point. Beyond the hill is a side track to Love Beach. This "must-do" detour is a highlight. We are glad to dive into the crystal clear, tepid water of this pristine bay.
The final stage of the walk is under a jungle canopy and we appreciate the coolness of a fresh sea breeze. Red and yellow parrots dart overhead. The only sounds are the incessant hum of cicadas, the whirr of dragonflies and the gentle lapping of Pacific waves on the sandy shore.
Outrigger canoes float gently on the turquoise ocean beyond the fringing reef. Tiny silhouetted figures in the low craft cast fishing nets. Banana boats skim past, leaving long lines of turbulent white water in their wake.
Energetic little boys splash in the shallows, glistening like ebony in the bright sunlight.
We're greeted by the boys' families. Their smiles reveal mahogany teeth and mouths stained by betel nut, which is chewed with leaves and lime as a digestive stimulant and narcotic. It has an extremely bitter taste so they carry a small bottle of finely ground coral, which they mix with the bitter nut to improve the flavour. I'm persuaded to try a nut but cannot stand the taste. I'm forced to spit out the red juice and flush out my mouth with water.
The locals take my betel intolerance in good part with a sprinkling of chortles and guffaws.
Getting there: P&O Cruises operates 10-day trips to the islands at the eastern tip of Papua New Guinea.
Further information: Doini Island Plantation Resort has bungalows at $200-$300 a night with three meals for $80 a day. Activities include snorkelling, fishing, kayaking, horse riding, turtle-spotting and bird watching.
The writer travelled on the Pacific Dawn courtesy of P&O Cruises and Air New Zealand.