The land masses continued to move apart, riding on separate plates, until they reached the positions they currently occupy. These continents are still on the move today. Exactly what drives plate tectonics is not known. One theory is that convection within the Earth's mantle pushes the plates, in much the same way that air heated by your body rises upward and is deflected sideways when it reaches the ceiling. Another theory is that gravity is pulling the older, colder, and thus heavier ocean floor with more force than the newer, lighter seafloor.
Trenches are the deepest parts of the ocean floor and are created by subduction.
Some of this molten ocean floor makes its way to Earth's surface, producing volcanoes. Most of it, though, becomes part of the Earth's mantle, perhaps to reappear much later at a distant divergent boundary. All hotels in the Arenal Costa Rica area are at a safe distance of the volcano, but hiking on the volcano beyond the warning signs is extremely dangerous. The toxic hot gases released during an eruption are traveling very fast, faster than you can run. The volcan Arenal is active everyday since 1968, but major eruptions forcing an evacuation is not common.