The sun is slowly setting as the boat chugs back towards the jetty, its wake forming the shape of an arrow in the calm water, pointing the way home.
I'm up on a hill in the same place I have been for the last few hours, looking out over the bay, beer in hand, watching for the hardy adventurers to return.
Soon they'll be up here at the resort with stories to tell, of the storm that hit them on the journey back, of waves piling over the bow, of the calm before that, of the experiences they had below the surface.
They'll have that glazed look of the obsessive about them, of people who couldn't care less what the weather was like or what the bookend boat trips contained, as long as they got their fix.
You meet nutters of all descriptions when you travel, those who chase their passion around the world - ski nutters, hiking nutters, food nutters, cycling nutters.
These particular nutters, the ones with the goggle marks on their faces and the rubber pipes slung over their shoulders, are diving nutters.
Underwater nutters. They've come here to Tawali in Papua New Guinea for one reason: to scuba dive.
There's a group of them, about 12 Sydneysiders, and they get together once a year for the sole purpose of travelling to some exotic location and going under the sea.
They've done Thailand and Belize, the Red Sea and the Bahamas. They've seen wrecks and fish and coral and rocks the world over. It's their only holiday of the year: diving.
They're staying at Tawali for eight days, seven of which they'll spend commandeering the resort's boat and doing four dives a day - occasionally five if they feel they can squeeze in another dunk at night.
They'll spend almost as much time breathing compressed air as they will breathing the fresh sea breeze up above.
This evening they clump up the wooden staircase to the restaurant building glowing with a mix of satisfaction and sunburn.
They're headed for the TV room, where they'll review a slideshow of the snaps they got under the surface today, remembering those rays, that shark, that nudibranch, those coral bommies.
I used to be a nutter, in much the same vein as these guys, except I was a snow nutter. For a good five or six years I spent all of my savings and all of my annual leave on one thing only: snowboarding. It didn't matter that I wasn't very good at snowboarding, it only mattered that I loved it.
I went to Thredbo, I went to Perisher, I worked a season in Colorado, I spent some time in New Zealand and I even made it to Japan. I spent huge amounts of money on my powder obsession. I broke one collarbone, dislocated one shoulder and damaged one ego.
Eventually I gave up.
Not entirely, but I replaced it with things like food and the adventure that can be found in the developing, non-snow-covered world. That's where most of my time and money goes these days.
For this group of divers, however, their obsession has never abated. Their travelling lives still revolve around the opportunity to pull on a skin-tight suit, don a mask and get wet with the fishies. That they've chosen to do this in PNG is no accident.
These guys know their scuba-diving and this area just near Milne Bay in the country's north-east is the place to go scuba-diving.
It has crystal-clear water, an abundance of marine life and almost unbelievably beautiful corals, these octopus's gardens of every colour you can imagine. I've seen them.
I'm just a two-dives-a-day type of traveller but this morning I was out on Deacon's Reef, which has to be one of the best dive sites in the world. There was 30 metres of visibility down there, lighting rock gorges covered in neon-bright fan coral, tiny nudibranches fluttering past, moray eels poking their scary little heads out of rocky holes.
And all this without a soul around, the nearest diver probably a few hundred nautical miles away.
You can see how contagious this is, how you could become obsessed with a travelling life lived under the sea. It's peaceful and beautiful. Stress-free.
But everyone has to come up to the surface eventually.
This evening, for a few hours with a cold beer or two, the fixation of our diving group has abated as talk turns to other topics.
It'll be back about 5am tomorrow though, when wetsuits are donned and engines are fired, when the boat chugs back out of the bay, lit by the gently rising sun, off to fuel an obsession again.
The writer was a guest of Papua New Guinea Tourism Promotion Authority.
Are you a travel nutter with a passion you pursue around the world? Post your stories and comments below.
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