Seawater is significantly saltier than the water in human bodies.
Human urine is essentially as salty as the water in human bodies.
This means that if you drink seawater either you accumulate salt in
your body, or you expel more water than you take in.
And, in general, humans DON'T accumulate salt in their bodies when
drinking seawater.
So, drinking seawater, rather than quenching your thirst, causes you
to become dehydrated.
Also, salt water is a low-grade emetic (causes you to throw
up). This is an additional means by which drinking seawater can
dehydrate you.
Severely dehydrated individuals do show signs of dementia, including
but not limited to hallucinations..
US$500 fee for receipt of unsolicited commercial email. USC 47.5.II.227