Why are there small islands far away from continents?

Question

Per my understanding, the ocean is largely very deep.

I can understand why there might be small, not-mountainous islands near the coasts of major landmasses, as it would only take a marginal elevation anomaly to create one there, but: How do places like Polynesia exist?

In: Other

Answer 1

Volcanoes that erupt on ocean floor many times over millions of years until the piling up of hardened lava eventually climbs above sea level.