Originally posted by John Bull
And they tend to be folk who explore independently and lose track of the time, or mis-judge journey time, or don't make a reasonable allowance for delays, or misunderstand back-on-board time, or foul-up ship's time vs port time. Alcohol is often involved. Even exploring independently, its exceptionally rare that a cruiser with a modicum of common sense misses a sailing.

And I've not read a single incidence on Cruise Critic of anyone on a private tour missing a sailing.

This is so true. It tells you nothing about independent tours to say that x people were late for the ship, when the majority of them were likely not on an independent tour anyway. They're far more likely to have stayed too long at the beach or in a local bar, or haven't sufficiently researched availability of taxis etc.

When you think of it, these independent tour companies would go out of business very quickly if they didn't get people back to the ship in time. If you book with an established tour company that you've seen recommended on this forum, you should be quite safe. You should also be OK to DIY if you remember a couple of things. Do your research thoroughly before your trip and go to the furthest point first and work your way back towards the ship and aim to be back well before the cut-off point. I'm always back at least an hour before the ship is due to sail. I have done very few ship's tours but I have never come remotely near missing the ship.