There's a reason people tell other people - usually those who have a thing about heights - not to look down.
The media have been invited to take a first-look tour of part of the City Rail Link project in downtown Auckland. We're standing above a huge hole that is about 12m deep. When the work is done, it will be at a depth of 18m.
The hole is a launch shaft on the corner of Victoria and Albert streets; where tunnel boring machines are due to start pipe-jacking - or micro-tunnelling - through for a new storm water main being constructed on the other side of Albert St.
Several journalists and cameramen make up the team which is escorted on to a temporary path that winds around the shaft.
We are warned of "trip dangers'' in the form of straps and pieces of metal that sometimes cross over the path - which although secure, is way too wobbly for a person who has a thing about heights.