1. Fill in the blanks - Hydrothermal vents form at locations where meets .

WHERE SEAWATER MEETS MAGMA.

Explanation: Hydrothermal vent is a hot spring on the floor of the ocean mostly along the central axes of the mid-ocean ridges, where heated fluids emerge from fissures in the Earth's crust.  Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart at spreading centers, ocean basins, and hotspots.

Hydrothermal vents have led to the formation of exploitable mineral resources via deposition of seafloor massive sulfide deposits.