Two different answers, depending on whether you take the boat.
On the walkways: damp
Spray and mist carry a long way from water moving at that volume, and the Lower Circuit takes you closest, there is a stretch where you are walking beside a waterfall rather than looking at one. Expect to come off it damp, with a wet camera lens. Not soaked. A light waterproof jacket covers it, and the ponchos sold in the park help, though only so much.
On the Gran Aventura boat: soaked
Not a splash. The speedboat runs into the spray beneath the falls and people come out completely drenched, laughing. Plan for it properly:
- A full change of clothes, including shoes, spending the rest of the day in wet shoes is the mistake people regret
- A swimsuit underneath, which saves a lot of awkward changing afterwards
- A dry bag for anything that must stay dry. One is usually provided for essentials on the boat; bring your own for the rest
- A towel
Your passport
It travels with you all day, and it is the one thing that must not get wet. Put it in a zip-lock or a dry bag in the morning and leave it there. Between the spray, the humidity and the chance of a sudden downpour, “it will be fine in my pocket” is not a plan.
If you are undecided about the boat, pack for it anyway. One plastic bag keeps the option open, and it is the part most people rate highest.
