El Calafate glacier tours: into the ice.

From the port the boat sails through the Upsala channel among icebergs, about 105 minutes of sailing, and on to the Spegazzini Glacier, another 105 minutes or so. Then it lands at the Spegazzini base, where you can walk the walkways to the Agostini viewpoint, visit the refuge and eat with a view of the ice.

Count on roughly 10 hours door to door; commentary on board comes from a guide speaking both Spanish and English. The national park entrance ticket is required and not included, and neither are food and drinks, so buy the ticket online the day before and pack a lunch. Bring sunglasses, a camera and clothes for wind and cold.

The reason is the ice. The park protects part of the third-largest continental ice field on the planet today, and glaciers flow out of it in every direction. Some end on land, others in the lakes, where their fronts break into icebergs that drift for days across the water.

The north arm of Lago Argentino is where this is most visible from a boat. The channels are narrow, the walls steep and the ice close, and every turn of the boat reveals another glacier hanging from the peaks above.

Several reviewers recommend paying extra for the Captain's Club upgrade, describing more comfort, better views from private balconies, and food and drinks included. One guest noted that the lower deck felt crowded by comparison, which is worth knowing if comfort matters to you.

Practical tips come up too. A reviewer suggests bringing your own food, since things on board felt expensive, and another advises picking a good spot and staying there, because the boat turns often. Good communication from the operator and help with the park ticket also earn praise.

Summer days are long. At mid-January the sun is above the horizon for 15.9 hrs, and average daily highs in El Calafate reach 20.2 °C. In October, early in the season, highs average 14.5 °C. On the water it always feels cooler than in town.

Autumn brings color to the forests of southern beech, which turn yellow, ocher and red around the lakes. The park authority describes it as a multicolored landscape, and on the Spegazzini walkways it adds a warm frame to the blue of the ice.

Captains adapt to conditions, and floating ice decides how close a boat can safely come to a glacier front on a given day. That is part of sailing among glaciers rather than a fault of the trip, and it is why patience and warm clothes matter more than a perfect forecast.

If you feel seasick easily, sit near the middle of the boat, look at the horizon and step outside for fresh air on the sheltered side. Most of the sailing is in long, open arms of the lake, and the views are worth a little discomfort.

The boat trips from Punta Bandera are booked in advance in El Calafate, a park access fee is paid, and a transfer to the port can be booked if you have no car, according to the park authority. Reviewers who chose the Captain's Club upgrade speak warmly of it, so check the options when you book.

Buy the national park entrance ticket online before your day: it is required and not included in the tour price. Keep your confirmation and park ticket on your phone, and check the pickup details the evening before.

Include something for scale. A boat, a person on the walkway or a gull on an iceberg makes it possible to understand the size of the Spegazzini front, which the operator puts at 135 m high. Without a reference, a huge wall of ice can look surprisingly small in a picture.

Keep your camera ready on deck as the boat turns headlands; views change fast. Protect your gear from spray with a cloth or a small dry bag, and bring a charged spare battery, since cold drains batteries quickly.

Add a warm hat, gloves and a scarf or neck gaiter for time on deck. Wear comfortable shoes with grip for the walkways at the Spegazzini base, where paths climb gently through the forest to the viewpoints.

Sunglasses and sunscreen are essential: light reflected off ice and water is strong even on cloudy days. A small backpack for your lunch, water and a spare layer completes the kit.

One reviewer appreciated the many explanations in both languages during the day. If you have questions, ask during the quieter moments of the sailing; guides are happy to talk about the ice once the boat is underway.

Learning a few words of Spanish goes a long way in El Calafate, from ordering coffee on board to chatting with the staff at the refuge, and people appreciate the effort.

On a calm evening a walk along the lakeshore toward Laguna Nimez is the perfect way to unwind after a day on the water. On a windy one, the Glaciarium explains how glaciers form and move, which makes your photos from the boat even more meaningful.

For something different, other El Calafate excursions include estancia dinners, horse rides on the steppe and kayaking on the lake. Our guide to what to see in El Calafate lists them with prices.

The caveats are worth knowing. The day is long, food is not included, the park ticket is extra, and wind can make the deck cold. Reviewers mention a crowded lower deck, and some recommend the Captain's Club upgrade for more space.

If you want a shorter boat tour from El Calafate, the ride below the front of the Perito Moreno leaves from a port inside the park, lasts about an hour and is sold from $62. If you want the full north arm with icebergs and a walk at the Spegazzini, this is the trip.