Zorientowałem się, jak mieć wiele markerów z oknami informacyjnymi, ale nie zamykają się po kliknięciu innego markera, wierzę, że to dlatego, że tworzę nowe okno informacyjne dla każdego markera, każda pomoc byłaby doceniana.

    <script type="text/javascript">


var map ;
  function initialize() {
    var latlng = new google.maps.LatLng(53.063165, -3.205390);
    var myOptions = {
      zoom: 6,
      center: latlng,
      mapTypeId: google.maps.MapTypeId.SATELLITE,
      zoomControl: false,
      mapTypeControl: false,
      mapTypeControlOptions: {
          style: google.maps.MapTypeControlStyle.DROPDOWN_MENU,
          position: google.maps.ControlPosition.LEFT_CENTER
      },
panControl: false,
streetViewControl: false,
      streetViewControlOptions: {
          position: google.maps.ControlPosition.LEFT_CENTER
      }
};
    map = new google.maps.Map(document.getElementById("map_canvas"), myOptions);

  var marker = add_marker(56.747923,-3.717155,"Ben Vrackie","<b>Ben Vrackie</b><br><br>Perthshire classic! some sweet hidden gems on this loop.<br> surrounded by amazing countryside, Lochs, hills this<br>has it all... Red Grade."); // pass in as Latitude, then Longitude
    marker.setMap(map);

   var marker = add_marker(57.556366,-5.409222,"Torridon Forest","<b>Torridon Forest</b><br><br>Technical and breathtaking.... <br>Black/red grade."); // pass in as Latitude, then Longitude
    marker.setMap(map)
}


  function add_marker(lat,lng,title,box_html) {

    var infowindow = new google.maps.InfoWindow({
        content: box_html
    });

    var marker = new google.maps.Marker({
          position: new google.maps.LatLng(lat,lng),
          map: map,
          title: title
    });


    google.maps.event.addListener(marker, 'click', function() {
        infowindow.open(map,marker);
});
return marker;
  }



 </script>