At Sulphur Banks (Ha'akulamanu), volcanic gases seep out of the ground along with groundwater steam. These gases are rich in carbon dioxide, sulfur dioxide and hydrogen sulfide -- the gas that smells like rotten eggs. Some sulfur gases deposit pure crystals at Sulphur Banks. Other sulfur gases form sulfuric acid which breaks down the lava to clay. This clay is stained red and brown with iron oxide. Visitors with heart or respiratory problems (such as asthema), pregnant women, infants, or young children should avoid this walk.
20160220 Volcano National Park Jane Mchan Fletcher Steele steam vents