Sailing around icebergs akin to icy phantoms, you approach the giant San Rafael glacier at the far end of the lagoon. Over 4km wide, and rearing out of the water to a height of 70m, it really is a dizzying sight. While the cruise boat keeps at a safe distance, you’ll be given the chance to get a closer look from an inflatable motor dinghy – but not too close, as the huge blocks of ice that calve off into the water with a deafening roar create dangerous waves. What you can see from the boat is in fact just the tip of the glacier’s “tongue”, which extends some 15km from its source.
The glacier is retreating fast, however, frequently by as much as 100m a year. Early explorers reported that in 1800 the glacier filled three-quarters of the lagoon, and archive photographs from the beginning of the twentieth century show it as being far longer than it is today. It is estimated that by the year 2030, the glacier will be gone.