Mountain climbing (or mountaineering) is one of my more challenging pursuits. To date, I've climbed seven major mountains, in addition to numerous hikes up lesser peaks.

1. Mount Whitney, California - October 1998.
   14,494 feet / 4,418 metres
   Highest mountain in the contiguous 48 States.
   
2. Mauna Loa, Hawaii - August 1999
   13,677 feet / 4,169 metres
   Largest mountain on Earth.
   
3. Mauna Kea, Hawaii - August 1999
   13,796 feet / 4,205 metres
   Tallest Mountain on Earth.
   
4. La Malinche, Mexico - December 1999
   14,640 feet / 4,462 metres
   
5. Citlatepetl, Mexico - January 2000
   18,405 feet / 5,610 metres
   Also known as El Pico de Orizaba
   Third highest mountain in North America.
   
6. Cotopaxi, Ecuador - December 2000
   19,347 feet / 5,897 metres
   Highest active volcano on Earth.
   
7. Chimborazo, Ecuador - January 2001
   20,561 feet / 6,267 metres
   Farthest point from the centre of the Earth.
   

You can find more detailed information on these and other mountains at the Peakware World Mountain Encyclopedia.