it was a white-knuckle ride

It was a white-knuckle ride is the term used when someone wants to say that they survived something threatening with very strained endurance in which they had to hold on tight. If you are gripping hard on something for an extended period of time, your knuckles will typically turn white which is where this phrase originates. If something is a white-knuckle ride, it is something you had to endure with hard work but got through it.