Koh Samui jeep safari, jungle to summit.

The day has been reviewed by 3,321 travelers on GetYourGuide, and the pattern in the newest reviews is easy to read. People talk about the guide and driver, the lunch with a view over the island and the off-road stretches through the hills. Several call it a high point of their time in Thailand, and families describe teenagers enjoying it as much as the adults.

One detail comes up more than any other. Reviewers describe a water fight between the jeeps, with giant water guns, near the end of the day, and some note that it was not advertised. We cannot promise it, because the listing does not mention it, but if you are bringing a camera or a phone, a waterproof pouch is a sensible precaution. A change of clothes or a towel is a sensible second precaution, as one traveler suggests.

Reviewers also mention pace and groups: some travel in several jeeps together, and others like that the group is small while meeting people at each stop. Another points out that a dry summer shrank the waterfall, though the pool was still welcome for a dip. Read the reviews on the booking page for the dates closest to your own.

Start with the water. Cool bottled water is supplied free on the day, and other drinks can be bought on the spot, so a little cash is useful. A hat and sunscreen suit the open jeep, and a light layer is sensible if rain is in the forecast. Shoes that grip are the most useful item, since the waterfall rocks can be slippery.

Next, the swim kit. Wear swimwear under your clothes, and pack a towel and a dry bag for damp clothes, as one reviewer advises a change of clothes. A waterproof pouch for your phone is a small purchase that protects your photographs.

Finally, the temple kit. A top with sleeves and shorts or a skirt that cover the knees keep the Mummified Monk and Wat Teepangkorn stops simple, and shoes that slip off easily help at the doors. Small baht notes cover the Secret Buddha Garden entrance of THB 80 per person. Everything fits in a small backpack that rides on your lap.

The day suits travelers who like a long, varied outing and can take a bumpy ride. It works for couples, friends and families with children who enjoy a swim and a long sit in a jeep; children must be accompanied by an adult. It also suits anyone who would rather not hire a scooter to see the hills.

The caveats are real. The tourism authority calls the inland dirt roads often bumpy, and a rival 4x4 listing rules out pregnant travelers, wheelchair users and guests with back or neck problems for its bumpy mountain tour. For someone in that position, a half-day highlights tour by minivan from $28 or a private car and driver from $67 is the gentler choice.

The day is also long, 6 to 7.5 hours, which is a lot if you are tired from travel. Our advice is to book it for your second or third morning, when the jet lag has gone. If you are unsure, hold the date with reserve now and pay later, and cancel free up to 24 hours ahead if the plan changes.