Google Map API v3 — set bounds and center

I've recently switched to Google Maps API V3. I'm working of a simple example which plots markers from an array, however I do not know how to center and zoom automatically with respect to the markers.

I've searched the net high and low, including Google's own documentation, but have not found a clear answer. I know I could simply take an average of the co-ordinates, but how would I set the zoom accordingly?

function initialize() {
  var myOptions = {
    zoom: 10,
    center: new google.maps.LatLng(-33.9, 151.2),


    mapTypeId: google.maps.MapTypeId.ROADMAP
  }
  var map = new google.maps.Map(document.getElementById("map_canvas"),myOptions);

  setMarkers(map, beaches);
}


var beaches = [
  ['Bondi Beach', -33.890542, 151.274856, 4],
  ['Coogee Beach', -33.423036, 151.259052, 5],
  ['Cronulla Beach', -34.028249, 121.157507, 3],
  ['Manly Beach', -33.80010128657071, 151.28747820854187, 2],
  ['Maroubra Beach', -33.450198, 151.259302, 1]
];

function setMarkers(map, locations) {

  var image = new google.maps.MarkerImage('images/beachflag.png',
      new google.maps.Size(20, 32),
      new google.maps.Point(0,0),
      new google.maps.Point(0, 32));
    var shadow = new google.maps.MarkerImage('images/beachflag_shadow.png',

      new google.maps.Size(37, 32),
      new google.maps.Point(0,0),
      new google.maps.Point(0, 32));


      var lat = map.getCenter().lat(); 
      var lng = map.getCenter().lng();      


  var shape = {
      coord: [1, 1, 1, 20, 18, 20, 18 , 1],
      type: 'poly'
  };
  for (var i = 0; i < locations.length; i++) {
    var beach = locations[i];
    var myLatLng = new google.maps.LatLng(beach[1], beach[2]);
    var marker = new google.maps.Marker({
        position: myLatLng,
        map: map,
        shadow: shadow,
        icon: image,
        shape: shape,
        title: beach[0],
        zIndex: beach[3]
    });
  }
}

Yes, you can declare your new bounds object.

 var bounds = new google.maps.LatLngBounds();

Then for each marker, extend your bounds object:

bounds.extend(myLatLng);
map.fitBounds(bounds);

API: google.maps.LatLngBounds

Got everything sorted - see the last few lines for code - (bounds.extend(myLatLng); map.fitBounds(bounds);)

function initialize() {
  var myOptions = {
    zoom: 10,
    center: new google.maps.LatLng(0, 0),
    mapTypeId: google.maps.MapTypeId.ROADMAP
  }
  var map = new google.maps.Map(
    document.getElementById("map_canvas"),
    myOptions);
  setMarkers(map, beaches);
}

var beaches = [
  ['Bondi Beach', -33.890542, 151.274856, 4],
  ['Coogee Beach', -33.923036, 161.259052, 5],
  ['Cronulla Beach', -36.028249, 153.157507, 3],
  ['Manly Beach', -31.80010128657071, 151.38747820854187, 2],
  ['Maroubra Beach', -33.950198, 151.159302, 1]
];

function setMarkers(map, locations) {
  var image = new google.maps.MarkerImage('images/beachflag.png',
    new google.maps.Size(20, 32),
    new google.maps.Point(0,0),
    new google.maps.Point(0, 32));
  var shadow = new google.maps.MarkerImage('images/beachflag_shadow.png',
    new google.maps.Size(37, 32),
    new google.maps.Point(0,0),
    new google.maps.Point(0, 32));
  var shape = {
    coord: [1, 1, 1, 20, 18, 20, 18 , 1],
    type: 'poly'
  };
  var bounds = new google.maps.LatLngBounds();
  for (var i = 0; i < locations.length; i++) {
    var beach = locations[i];
    var myLatLng = new google.maps.LatLng(beach[1], beach[2]);
    var marker = new google.maps.Marker({
      position: myLatLng,
      map: map,
      shadow: shadow,
      icon: image,
      shape: shape,
      title: beach[0],
      zIndex: beach[3]
    });
    bounds.extend(myLatLng);
  }
  map.fitBounds(bounds);
}