Natural Wonders

You should make a bracha on Niagara Falls because it is a unique river and mountain which you can see the power of Hashem in it. When you see the rock mountains you should a make a bracha. When you see the Pacific Ocean you should make a bracha. Even if you don’t go to the bottom of the Grand Canyon you should make a bracha .
The Gemara in Brachot 54: For extraordinary mountains, hills, seas, rivers, and deserts, one recites: Blessed…Author of creation. Rabbi Yehuda says: One who sees the great sea recites a special blessing: Blessed…Who made the great sea.

The Shulchan Aruch 248 rules like the Mishna and Gemara One should Shulchan Aruch the bracha: Baruch Attah Hashem Elokeinu Melech Haolam Oseh Maaseh Beraishit on seas and rivers, tall mountains, and deserts.
The Meforshim explain the bracha of Oseh Maaseh Beraishit, that Hashem did Maaseh Beraishit is because when we see the se great deserts or mountains etc. which were there from the time of Maaseh Beraishit it reminds us of it.
There is a discussion amongst the Psak if one makes a bracha only on these things or anything which gives a person a sense of awe and wonder. The Bet Yosef quotes the Abudraham the name of R’ Shimshon only make a bracha on mountains and rivers which are unique or extreme or large rivers which remind a person of the fac that Hashem made them. So rules the Shulchan Aruch 228:3: Not on any mountain or hill do you make a bracha only one those mountains and hills which are different and the power of Hashem is apparent in them.
So a person would make a bracha on tall maintains no matter what. So when you see the Rocky Mountains you should make a bracha. To see Niagara falls one would also Shulchan Aruch a bracha because it is river which is different and unique and you can see the power of He in it. Sequoia trees are not as old as Maaseh Beraishit so even though you may be awed by them those trees were not formed themselves during Maaseh Beraishit so you do n to make a bracha. Seeing a Geyser as well is not a mountain or river so you wouldn’t say a bracha.
The question is what about the Grand Canyon. If you were standing at the bottom the Grand Canyon with the cliffs towering over you it is like any other very tall mountain. The Mor Uketziah write that tall cliffs one makes a bracha as well, but he probably meant if you are at the bottom. However if you can see to the bottom of the canyon or gorge you should still be able to tell there is a cliff or a mountain you may make a bracha because it would still remind you of Maaseh Beraishit. A slot canyon however which on ground level looks like a gash in the ground you would probably not be able to make a bracha until you use it from the bottom and you can see the tall cliffs.
When you reach the Pacific Ocean you say a bracha of Oseh ET HaYam HaGadol. The Mishnah says we say Oseh Et HaYam Hagadol on the Yam Hagadol. There is a Machloket whether this refers to the Mediterranean Sea since it is next to Eretz Yisrael it is called ‘Great’. Others say it refers to the Yam Hagadol, the ocean. We rule that one must make a bracha of Oseh et HaYam Hagadol on the ocean. On other seas and large lakes you say Oseh Maaseh Beraishit.