[whatthefuck123]

go to the water and type /save
then go to your file last line (savedpositions.txt) and get your 3rd coord

pawn Код:

public OnPlayerUpdate(playerid)
{
new Float:z;
GetPlayerPos(playerid, z,z,z);
if(z<=/* ur coord*/)
{
   SendClientMessage(playerid, -1, "your in water");
}
return 1;
}

i hope you understand i cant make it clearer..