The Shulhan Aruch (Orah Haim 228) writes that one when sees tall mountains, he recites the Beracha, "Baruch At Hashem Elokenu Melech Ha’olam Oseh Ma’aseh Bereshit," praising Hashem for creating such an impressive world. The Beracha should be recited with the complete standard text of a Beracha (including "Hashem Elokenu Melech Ha’olam").
Over which mountains in particular is this Beracha recited?
Hacham Bension Abba Shaul (Israel, 1923-1998), in his work Or Le’sion, writes that in Israel, one who sees Mount Hermon recites this Beracha. The Halachic authorities add that the Beracha is also recited upon seeing the Himalayas, the Rocky Mountains and the Swiss Alps. There is some discussion as to whether the Beracha should be recited upon seeing the large mountains in the area of Rome. The Gemara relates that Rome did not exist at the time of the world’s creation, and it was formed later. On the day King Shelomo married Pharaoh’s daughter, the Gemara tells, G-d was angry and sent the angel Gabriel to thrust a stick in the Mediterranean Sea. Ground eventually formed around this area, and this became Italy. Thus, as the region was not included in G-d’s original creation, one cannot recite the Beracha of "Oseh Ma’aseh Bereshit" in reference to its mountains.
Another interesting question discussed by the Poskim relates to the recitation of the Beracha upon seeing the Grand Canyon. Geologists claim that the canyon was formed over time by the Colorado River, and thus did not exist at the time of creation. However, they believe that this process occurred over the span of hundreds of thousands of years, while we believe that the world is not that old. Therefore, we may assume that the Canyon has existed since creation, and thus the Beracha is recited.
One recites this Beracha upon entering the stalactite caves in Israel, which are very impressive and have been in existence since the time of creation.
Rav Haim Kanievsky (contemporary) addresses the question of whether one recites this Beracha upon seeing impressive mountains from the window of an airplane. He concludes that the Beracha is not recited from an airplane, since one cannot appreciate the height of the mountains when viewing them from the air. This is, indeed, the accepted Halacha.
There is a debate among the Halachic authorities as to whether one recites the Beracha upon seeing a mountain if the mountaintop is not visible due to fog. In light of this debate, one should not recite the Beracha in such a case.
Summary: One who sees a large, majestic mountain recites the Beracha of "Oseh Ma’aseh Bereshit." This would apply to the Himalayas, the Swiss Alps, the Colorado Rockies, Mount Hermon in Israel, the Grand Canyon, and stalactite caves. The Beracha is not recited if one views the mountains from an airplane, or if the mountaintop is concealed by fog.
