Sea salt water and blood plasma have almost identical chemical compositions of mineral and trace elements. If white blood cells were to be removed from the body and placed in sterile, diluted seawater, they could pretty much function as usual.
Sea salt water is packed full of numerous skin-healing minerals. Magnesium, calcium, and potassium help to absorb toxins in the body and promote the healing process. Magnesium is an anti-inflammatory and antimicrobial agent, effective at getting rid of acne. Additionally, sulfur in sea salt water is a natural antiseptic -- many acne masks today contain this active ingredient.
Sea salt is a natural exfoliant. When you hang out in the ocean, the salt helps to slough off dead skin and promote healthy skin cell production. Combined with the coarse sand, all of the dead skin on your body should be noticeably reduced at the end of a beach day! The minerals from the ocean also help with exfoliation. The minerals open pores that then are able to get extra deep clean. While also encouraging blood flow, this also helps serums and moisturisers to be easily absorbed into the skin.