private["_n", "_m"];
//Set zone around island
for "_n" from 18 to 48 do {
for "_m" from 20 to 47 do {
_ps = [_m*100+50, _n*100+70];
_marker = createMarker [format["Marker-%1-%2", _m, _n], _ps]; //Offset for grid
_marker setMarkerSize [50,50]; // Size
_marker setMarkerShape "RECTANGLE";
_marker setMarkerType "SOLID";
   if (!surfaceiswater _ps) then {
    _marker setMarkerColor "ColorRed";
   } else {
    _marker setMarkerColor "ColorBlue";
   };
_marker setMarkerAlpha 0.3;
sleep 0.001;
};
};
hint "all done!";