Watch water burn at Arçivan village! What you see is a stand-pipe beneath a concrete pergola, but the water that bubbles forth is made ‘flammable’ by partly dissolved methane. You''ll need to bring your own matches as the flames blow out fairly rapidly and locals care more for collecting the water to drink.
The spring is beside the main Lənkəran road, 9km north of Astara. Astara–Lənkəran taxis are usually happy to stop for a couple of minutes en route.