On your marks, get set, go... Registration for what will be one of 2017’s most popular races, The North Face 100, is now open.

The challenging 100km race will take place on Feb 4, 2017, taking runners through a tough, remote trail in Khao Yai. This is the real deal: You have to be very cautious, keep track of your energy levels and stay hydrated as water stations are only available every 10km. This year's event sold out super-fast.

Only experienced runners can join the 50-100km races, so make sure you meet the criteria before signing up. Not-quite-as-hardcore runners can choose to run shorter distances: 15, 25, 50 and 75km. Beware that these races are more challenging than regular tracks, too—so be sure to train properly.

Early bird entry rate applies until Aug 26 (from B900 for 15km race). After that, the rates go up to B1,200 (15km race)-B3,400 (100km race). Each runner will receive a race kit, which includes bib number, timing chip, emergency contact sheet, course map sheet, complimentary drawstring bag and The North Face T-shirt. Space is limited to 3,200 runners only.

Register here or at any of the 10 North Face shops throughout the country. Registration for the 100km solo race is only open online. More details here.

Take a look at this past race video, if you're game.