Follow the signs to the sightseeing point where , on the predictably clear day , you can see acrose48 km ( 30 miles ) of blue ocean to La Desirade , 67 km ( 42 miles ) to Antigua , and even 77 km ( 48 miles ) to the ash-covered peaks of Montserrat .
Even on a clear day , you can hardly see your hand in front of your face .