"Alaska's Mendenhall Ice Caves provide a perfect romantic adventure for couples who thrive on dealing with a bit of danger. The caves, cut into the ice of Mendenhall Glacier by rivulets of water, glow a breathtaking blue that visitors often describe as 'otherworldly.' Bear in mind that these caves are rapidly melting due to climate change, so your romance may end up outliving them." - Travel + Leisure Editors