If it wasn't for the sea snakes or other marine menagerie lurking beneath, the emerald green lagoon would be positively worth a cool, refreshing dip.
Deep in the well of a partially hollowed-out limestone island, the glass waters in this "hong" lie undisturbed except, perhaps, by the ripples from our inflatable sea kayak.
For a few minutes, it is our private universe - save for the resident macaque monkeys, eyeing us suspiciously from their hidden perches around the walls.
Welcome to Panak Island and one of many such hongs (the Thai word for rooms) dotted throughout Phang Nga Bay, a marine reserve in the Andaman Sea nestling between Phuket, Phang Nga and Krabi provinces in the centre of Thailand.
Historically, the limestone crags were created after the Indian sub-continent collided with continental Asia around 30 million years ago.
Today, the only collisions are likely to be between competing tour company kayaks trying to squeeze in and out of the lagoons through sometimes claustrophobic cave tunnels.
Cruising in through one such tunnel, the hong opens up like something out of Jurassic Park or Tarzan, with Asian reticulated pythons dripping from the jungle canopy and who knows what other animal species hidden from sight elsewhere.
At some point in time, the limestone roof of this huge cavernous chamber collapsed, creating the hong, the sun shining new light into a lost world.
In the centre of the lagoon, a solitary mangrove rises on mangled tentacles from the water and for a few moments, it's a paradise of calm and serenity.
Suddenly, the silence is shattered by the sound of an invisible "something" crashing down through the leaves and branches 100 metres above.
Within seconds, a macaque can be seen flying 10 metres through the air from one vine to another before deftly landing on a rock on the waterline just metres from our kayak.
A second, older and much larger monkey appears alongside it a few seconds later, growling and obviously hungry.
They probably don't like getting wet, I reassure my wife who's sitting in front, closest to the edge and growing mildly concerned at the proximity of the new arrivals.
"They swim between the islands in Andaman (sea)," laughs our gleeful Thai guide Mike, as the first monkey plunges into the water towards us.
"They eat crab but also they like these food," adds the guide in the next canoe, waving a banana.
Of course, the monkey needs no further cue and gingerly pinches the banana from the tour guide's hands, while a third puts a piece of unpeeled banana on the end of his oar and leans out, offering it to yet another macaque that's swung by to check things out.
As it turns out, the monkeys are harmless; so too the nonchalant python stuck to the side of a rock wall nearby.
The reptile looks for all the world like a rubber toy snake stuck there for the benefit of us tourists.
Indeed, one bloke in the next kayak suggests just that, prompting Mike to paddle up to the wall, teasing the python gently with his oar in the hope of provoking a response.
It's all too much for my wife and the bloke's partner in the next canoe, who nervously motion our guides to move swiftly on, preferably away from the water's edge.
And so our tour continues, as we thread our way from island to island, hong to hong, from open sea into bat-infested tunnels and caves.
Some of the cave entrances are so low, with barely a metre between the ceiling and the water, that the only way in or out is to lie flat in our kayak.
More than 100 limestone islands litter Phang Nga Bay, including Koh Ping-gan better known as James Bond Island for its exclamation mark-shaped limestone tower which featured in the film, The Man With The Golden Gun.
While die-hard kayakers would probably relish the challenge, some of the islands are scattered too far apart for the mainstream tour firms to kayak between.
Instead, after visiting each sea cave, we return to the main boat before motoring on deeper into the Phang Nga marine reserve and the next hong.
We won't make it as far as James Bond Island today, much less the other main attraction (the superb scenery notwithstanding), Phang Nga's floating fishing villages which are built entirely on stilts.
But our itinerary does take in a remote island beach where, after an amazing hot and cold buffet lunch on board the boat, we are dropped off for an hour or so relaxing and sunbathing on the beach.
Such an exhausting schedule, even though our guides did all the paddling solo, and the coarse sandy beach on Lawa Island is a chance to stretch the legs and the beach towel before returning to Phuket.
IF YOU GO:
Thai Airways (www.thaiair.com) flies from Melbourne, Sydney, Perth and Brisbane to Bangkok's Suvarnabhumi Airport with connecting flights to Phuket.
Several operators, including Sea Cave Canoe (www.seacavecanoe.com), run half-day and day tours out on Phang Nga Bay.
A day trip with Sea Cave Canoe typically costs 2,900 Thai baht (approx. $NZ258) per person, or 1,450 baht per child and includes return transfer from hotel, tour guide-cum-paddler, refreshments, lunch, kayak trips to at least three different islands and insurance and park fees.
The Aquamarine Resort and Villa (www.aquamarineresort.com) at Kamala, Phuket, has rooms starting at 4,200 baht per night, subject to seven percent VAT and 10 percent service charge, with a minimum three nights stay required (effective up to October 31, 2007).
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