[SymonClash]

pawn Code:

IsPlayerUsingSwimAnim(playerid)
{
    switch(GetPlayerAnimationIndex(playerid))
    {
        case 1538, 1542, 1540, 1544, 1250, 1062, 1539: return true;
    }
    return false;
}

pawn Code:

if(IsPlayerUsingSwimAnim(playerid))
{
    SendClientMessage(playerid, -1, "You're in water!");
}
else
{
    SendClientMessage(playerid, -1, "You aren't in water!");
}