Final answer:
The Antarctic Peninsula, an extension of the Andes Mountains, extends south into the Pacific Ocean and contains twenty-nine active volcanoes, including Deception Island's volcano, which erupted in the late 1960s, and Mount Erebus, which has been active since 1972 with a large lava lake.
Step-by-step explanation:
The peninsula that extends south into the Pacific Ocean and contains twenty-nine active volcanoes is the Antarctic Peninsula, which is actually an extension of the Andes Mountains of South America. An example of volcanic activity in this region is the volcano on Deception Island that erupted in the late 1960s, destroying research stations. Sightings of lava flows have been reported demonstrating ongoing volcanic activity.
While the Baja California Peninsula is the world's longest peninsula, lying between the Pacific Ocean and the Gulf of California and includes the Peninsular Ranges, it is not known for twenty-nine active volcanoes. The geographical area known for a high concentration of active volcanoes is the Ring of Fire which describes the horseshoe-shaped zone around the Pacific Ocean where earthquakes and volcanic activity frequently occur. Mount Erebus located on Ross Island is the world's southernmost active volcano and has been active since 1972 with a large lava lake in its inner crater. The volcanic activity in this region contributes to the dynamic environment of the Antarctic Peninsula.