Flam is a very small settlement - you can see everywhere within 2 hours on foot.
Most people take a ride on the famous Flam Railway but it was booked up so far in advance that we couldn't secure tickets. We now know that it is best if you have not bought tickets to go straight to guest relations as soon as you board and to ask there. If there is still no availability, insist on being put on the 'Wait list' as it is sometimes possible to obtain extra tickets during the cruise. (We went straight to the desk as soon as we boarded and were probably the first to do so but the chap at Guest Relations put us off going on the 'Wait List' as he said there was little chance that more tickets would become available. He was wrong - and this was a major disappointment to us!
We took the Bergen Highlights excursion, which we enjoyed, but we arrived back at the ship just in time for the sail away at 2.00 pm - a far too early departure time from such an interesting port of call.
It is worth noting that the Celebrity ships now moor at the container terminal which is further away from the centre and no-one is permitted to walk freely into town from the ship because the area is 'restricted'. A free shuttle bus is provided from ship to town.