Just outside the national monument's boundary, on private land along NM-53, lies one of the strangest one-two combinations in the American Southwest: a perfectly preserved cinder-cone volcano next door to a permanently frozen ice cave. The Bandera Crater is one of the youngest of the El Malpais volcanic field — about 10,000 years old — and a short, steep trail leads up to a viewpoint on its rim.
The ice cave a short walk away is the show-stopper. Wooden steps drop down into the cool gloom of a collapsed lava tube where a frozen lake of pale green ice sits permanently below 0°C. The whole site is privately owned and charges admission (around US$15 per adult); the gift shop is unapologetically kitsch but the geology is the real deal. Combined visit takes a couple of hours. Wear sturdy shoes — the volcano trail is loose cinder.