LatLng latLng = new LatLng(42.237439, -8.714226);
    int radius = 10;

    CircleOptions circleOptions = new CircleOptions()
            .center(latLng)
            .radius(radius)
            .strokeColor(Color.parseColor("#0D47A1"))
            .strokeWidth(4)
            .fillColor(Color.parseColor("#AF4046FF"));
    Circle circle = mMap.addCircle(circleOptions);
    mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng, 17));

    mMap.addMarker(new MarkerOptions()
            .position(latLng)
            .title("Mision 1.")
            .snippet("Fundador: user")
       .icon(BitmapDescriptorFactory.fromResource(R.drawable.sound1)));
    mMap.setOnInfoWindowClickListener(this);
    mMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));

    Location location1p = new Location("mision1");
    location1p.setLatitude(42.237439);
    location1p.setLongitude(-8.714226);
    float distancia1 = locationGPS.distanceTo(location1p);
    lblPista.setText("Mts a mision1: "+distancia1);

private void localizacionPistas() {

    if(distancia1 <= 10){
        musicafondo.stop();
        guerra.start();
    }
}