Boats to Yaxchilán archaeological zone  (25 kilometers, 45 mins there/60 mins return) leave from a pier at the end of the main road, where a number of cooperatives and private outfits compete for arriving tourists. The trip is quite enjoyable, zipping down the river in a long colorful lancha with Guatemala on one side and Mexico on the other, and the chance to see birds, howler monkeys, and beefy crocodiles sunning themselves on the riverbank.
Round-trip prices are fairly uniform and depend on the size of your group: US$65 for 1–3 passengers, US$75 for four, US$95 for 5–7, and US$120 for 8–10. The price includes two hours at the site; you can stay longer, but you’ll have to tip the boatman (even better, throw in a Coke and something to eat as well).
If you’ve got time to kill, the Museo Comunitario Frontera Corozal (tel. 55/5329-0995, 8 a.m.–6 p.m. daily, free) is a small well-organized museum with a room about the history of the community, another on local customs, flora, and fauna, and a third on archaeological discoveries, including the museum’s pièce de résistance: two 3-meter, 3-ton stelae found in the surrounding forest, carefully restored, and installed here. Signage is in Spanish only.