My iPhone fell in the Sea

There’s not much one can say without seeing the extent of damage caused by sea water, but wherever salt water touches electronics, corrosion starts in no time. Cameras used by the Face ID recognition are not replaceable by anyone beside Apple, thus unless you can get an AASP to give you assistance, Face ID is gone for good.

Original and refurbished screens are now available in the market, but you’ll have to find a very reputable repair shop where they have the right tools, as also original screens need programming to keep brightness controls, truetone and reliable touch when transferred into a different iPhone.

If sea water managed to get in touch with any other part beside the screen, a proper decontamination has to be taken into account to have decent chances your iPhone will continue to work over time. It won’t be cheap, as there’s a lot of work involved even in the best of cases.