Question: Why are our tears and the sea salty?

Oli Wilson answered on 10 Nov 2017:

Tears are salty because they’re fluids from your body, and bodies actually aren’t great with pure water – it can make important chemicals like salt leave cells, or shove so much water into cells that they burst! So essentially all the fluids in our bodies are a bit salty – tears are no exception.
(A quick side note here to say that tears are more awesome than I ever knew! The thin layer of tears that’s always on your eye includes chemicals that fight bacteria, and when we cry tears of pain or sadness our tears start to contain a natural painkiller! Amazing.)
I realised that I didn’t actually know why the sea is salty so I looked that up too. It turns out that rainfall and rivers wash salt out of the ground and carry it to the sea, and it can’t escape easily (which is why the sea is saltier than the rivers that feed it). Some of the chemicals in sea salt also got released from the rocks under the ocean floor, either when the seas first formed or when underwater volcanoes erupt.
So different explanations for the saltiness in each case, as it turns out! And I learned a lot while finding out the answers 🙂