While it is not nice to spend time getting annoyed by security people, I learned a harsh lesson about what happens when the airline decided to send my luggage to Marseille in France instead of Egypt. Amongst others my perscription mask was in there. Up on arrival a bus ride was planned of six ours to the South of Egypt where in the middle of nowhere we'd embark on a ship. So I needed to rent a complete set in a village where diving was just starting. I went with three supporters to more than 5 shops to get gear, which later on would also have to be returned of course. Imagine my size 12 feet in a country of dwarfs. Luckily in my group was a guy who had week contacts, about my strenght, so that solved the mask issue. All in all the bus and my 16 fellow travellers had to wait for three hours to get everything sorted out for me. So since then everything that is vital like mask, camera, reg's go in the carry on. As diving the globe is now more commonplace then when this happened I never get a question but for the aluminium housing of my camera which shows up as a lump of metal the size of a shoe box.