function initMap() {
    mapDiv = document.getElementById('map');
    map = new google.maps.Map(mapDiv, {
        center: {lat: 51.9960464, lng: 5.8911804},
        zoom: 13,
        disableDefaultUI: true
    });
    var i;
    var location_halflength = Math.floor(locations.length / 2);
    for(i=0; i < locations.length; i++){
        marker = new google.maps.Marker({
            position: {lat: locations[i][1], lng: locations[i][2]},
            map: map,
            animation: google.maps.Animation.DROP,
            title: locations[i][0]
        });

        locations[i][3] = marker;

        if(i == 0){
            $("div.dropdown-locaties").append('' +
                '<ul class="dropdown-locaties-ul">');
        }

        if(i >= 0 && i <= location_halflength){
            $("ul.dropdown-locaties-ul").append('' +
                '<li onclick="setPos(' + locations[i][1] + ', '+ locations[i][2] +'); slideUp(\'.dropdown-locaties\'); setZoom(15)"><span>'+locations[i][0]+'</span></li>');
        }

        if(i == location_halflength){
            $("div.dropdown-locaties").append('' +
                '</ul>\n' +
                '<ul class="dropdown-locaties-ul">');
        }

        if(i > location_halflength){
            $("ul.dropdown-locaties-ul").next().append('' +
                '<li onclick="setPos(' + locations[i][1] + ', '+ locations[i][2] +'); slideUp(\'.dropdown-locaties\'); setZoom(15)"><span>'+locations[i][0]+'</span></li>');
        }

        if(i == locations.length){
            $("div.dropdown-locaties").append('' +
                '</ul>');
        }
    }
}