system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Where do those monster waves in the middle of the ocean come from?

Tsunamis get that big since the beach makes that the water has no space when going high up.
But those monster waves just exist on the oceans with hundreds of meters ocean dephts??
gpt
Research into this is ongoing. We know what can cause them sometimes, but we don't know what causes them all the time. They seem to happen most reliably in places where a strong current moves in the opposite direction of the waves, but we don't even know if that's what always causes them.

Fortunately we found out that they happen way more frequently than we thought. So we should get more answers in the near future. For now though, there's no really solid answer.