The 575-acre St Herman's Blue Hole National Park contains St Herman's Cave, one of the few caves in Belize that you can visit without a guide. The visitors center (where flashlights can be rented for BZ$3) is 11 miles along the Hummingbird Hwy from Belmopan. From here a 500yd trail leads to St Herman’s Cave. A path leads 200yd into the cave alongside an underground river – to go any further you'll need a guide.
Return via the Highland Trail, steep in places but with rope guides, for some nice views. Carry a strong flashlight and good insect repellent. If you're keen on a longer hike, there's a three-hour trail from here via Crystal Cave.
The Blue Hole, a 25ft-deep swimming hole, is about a mile further along the highway. Drive there, or take the 45-minute jungle trek from the visitors center. Admission is with the same ticket as St Herman's Cave.
Any bus along the Hummingbird Hwy will drop you at the visitors center or the entrance to the Blue Hole.