Snæfellsjökull is a stratovolcano with a glacier and is one of Snæfellsnes’s characteristics. It is beautifully shaped and is sometimes visible from Reykjavik. It's surrounding area is a National Park where it is popular to hike in good weather with a guide. It is also common to whale and bird watch throughout the peninsula.
If you've ever read Jules Verne's novel, A Journey to the Center of the Earth, in which the characters find the passage to the center of the earth on Snæfellsjökull.