Mountains and great volcanoes
Snowdon means Snow Mountain, therefor the lack of Mt infront of the name. It's the highest mountain in Wales and the highest mountain in UK south of the Scottish Highlands. There are two ways to scale Snowdon; either take the scenic train from Llaberis all the way to the summit (who says cheating?) or hiking along one of the six trails leading to the summit. The most popular trail is the Llaberis, starting from the train station in Llaberis. It normally takes 3-4 hours one way, but can be done in 2.5 hours (one way) if you set a good pace.
This mountain is one of the seven summits, the highest mountains of each continent. With an altitude of 6,194 m (20,320 ft), it is one of the most difficult ones to climb because of its altitude gain (for Mt. Everest, the base of the mountain is much higher) and the cold weather. There is some dispute about its name, officially called Mount McKinley, but locally known as Mount Denali. This disagreement is purely political. You don't have to climb this mountain to enjoy it. If the weather is clear you can see this mountain from Anchorage and it stays pretty much all the time in sight when you travel up North on Highway 3.
The highest mountain in Indochina (Laos, Cambodia and Vietnam) might seem as a easy trekking peak due to the not so impressive height of only 3,143 m, but don't be fooled. The are several routes to the top, but every track is difficult and involves a overnight stay unless you do commando raid (record is around 10 hours up and down from Heavens Gate at 1,949 m). A lot of scrambling on slippery rocks and zigzagging through dense bamboo forest is the norm, and expect bitterly cold and wet nights. To get the full experience, it's highly recommended to descend on the southeast side into the Sapa valley over multiples days. Coming down from the top covered in dense forest and trekking into the farmed valley with rice terraces and villages is a rewarding finish.
Since the beginning of 2016 you can just take the almost 6.3 km long cable car straight from Sapa.