Most volcanoes happen where?

Sixty percent of all active volcanoes occur at the boundaries between tectonic plates. Most volcanoes are found along a belt, called the “Ring of Fire” that encircles the Pacific Ocean. Some volcanoes, like those that form the Hawaiian Islands, occur in the interior of plates at areas called “hot spots.”

Explanation:

Pacific Ocean if u want a country then, Indonesia

Explanation:

but if u mean which planet then it's Venus.