Tephra-jet explosion, Kīlauea, Hawai‘i

A tephra jet is the most common type of explosion a visitor is likely to witness at an ocean entry, especially if a delta collapse severed an active lava tube. Waves rushing against the open stream of lava "explode" in a cloud of steam, hot water, molten spatter, and tephra fragments. The lava debris often builds a semicircular littoral cone several meters tall on a delta's leading edge.