On this page of the Halo Infinite guide you'll find information regarding how to unlock the Nosebleed achievement. This achievement is obtained in the campaign mode for checking out the best possible view. Here you'll find an explanation of where to go on the Zeta Halo map.
Best view in Zeta Halo - location
This achievement requires you to climb the tallest mountain in Zeta Halo you explore during the campaign.
The place where you unlock the achievement is shown on the pictures above. It's a mountain found in the map's north-west.
Reaching your destination
The mountain itself isn't guarded but climbing by foot could take a long time. You'd have to fast travel to one of the FOB bases close to the mountain and begin a long trip during which you should use the Grappleshot to catch onto higher platforms and the mountain's slope.
Using an aircraft is much simpler. You can wait until accumulating 2600 Valor points which grant you access to the Wasp. You'll be able to summon this machine in the FOB bases. You can also steal an enemy aircraft as well.
Whichever method you choose, you must climb up to the mountaintop and stand there for a few second to get the achievement.