North Sea
Yes I have flown on the S61 but for about 2 years flew on the chinooks from Aberdeen. I was able to fly in the cockpit jumps seat on many of the return journeys with headset all the way including landing.
I was aboard when we were struck by lightning and also when we required to make an emergency landing due to gear box failure.
Depending on the winds it could be in excess of 3 hours for the journey !