El Calafate is the gateway town for Los Glaciares National Park, sitting on the shore of Lago Argentino about an hour's drive from the glaciers. The town itself is small and tourist-oriented, but you are not here for the town -- you are here for the ice.
The star attraction is the Perito Moreno glacier. It is one of the most impressive natural sights in South America: roughly 5 km across and 60 m high at its face, and one of the few glaciers in the world that is still advancing. Stand on the viewing platforms and you will hear deep cracking noises from within the ice. Wait long enough and you will see huge chunks calve off the face and crash into the lake below, sending up waves that echo off the far shore. It is mesmerizing and you could easily spend half a day watching.
Beyond Perito Moreno, boat excursions take you past the Upsala and Spegazzini glaciers further into the park. El Calafate also makes a good base for hiking in the national park, though for serious trekking most people head north to El Chalten.