Now, this is interesting!

Seawater contains 230 billion tons of lithium, compared to just 21 million tons in conventional land-based reserves. Lihytech estimates that extracting just 0.1 per cent of all lithium from seawater would be enough to meet humanity’s technology needs.

Source: https://www.theengineer.co.uk/content/news/kaust-spinout-will-extract-lithium-from-seawater/