system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why doesn’t GPS work underwater?

If a satellite can pinpoint my location from SPACE, how come a (relatively) small amount of water prevents GPS from working?
gpt
Water absorbs radio waves across a considerable band of wavelengths.

It's so good at this that your microwave oven can quickly boil water by pelting it with radio.

Since the GPS is relying on radio communication to triangulate itself, it will lose contact quickly under water.