The lime green water shimmers in the sunlight like leaves in a morning breeze. We are motoring quietly through the bay, along with other similar boats, towards Sung Sot Cave, a large-ish limestone cave in one of the small, craggy islands that juts up out of the water. There are dozens of similar sites scattered throughout Ha Long Bay, but only two are open to the public.

It’s early, but the heat is already stifling. I can’t imagine having to work outside in this, but I suppose with enough time your body adapts. And if you grow up here, it likely just seems normal.

We arrive at the island and climb the hundred or so steps to the cave entrance, with our guide cracking jokes along the way. He’s an affable guide, and I like him.

Descending into the dark of the cave, I’m disappointed that the temperature isn’t becoming cooler. The air is still, and the humidity makes it heavy. Still, the cave itself is pretty spectacular. Reminiscent of Carlsbad Caverns, which I visited years ago on a motorcycle trip with my friend Colin. This is much smaller in scale, and not nearly so far underground, but is impressive all the same.

Our guide points out shapes resembling monkeys, sloths, the Buddha, and a turtle as we wind our way along the pathway, rising and falling as it meanders through the cave, as well as where the ceiling has caved in over the centuries as a result of earthquakes.

By the time we get back to the jetty and make our way to the boat I am soaked through with sweat. After a long, cold shower, I dry myself off and immediately begin sweating again. Thankfully it subsides before lunch.

Lunch is again spectacular: deep-fried fish in a lemon sauce; pork and mushrooms; calamari; a cucumber salad; jasmine rice; and dragon fruit for dessert. After lunch, we say goodbye to the crew and pile back into the gloriously air-conditioned bus back to Hanoi, where we’ll catch an overnight train to Hué — the next stop on our itinerary.

Until then…