system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is the ocean salty?
gpt
Salt and other minerals are leached out of rocks. Once in the ocean the salt has nowhere else to go so the salinity of the ocean slowly increases over time. Lakes and rivers are not salty (except for some exceptions) because they are continually supplied with fresh water, and they have outlets into other rivers or the ocean. Lakes that are salty have no outlet, so just like the ocean the salt builds up over time.