These birds are Grey Ternlets - Procelsterna cerulea. The images of this bird in my field guide do not do it justice, as it is shown with a rather bulky beak, and while you can see hints of this in my pictures I think the bird looks rather graceful. In fact, the way these birds have been captured here reminds me of swifts.
Theses birds are small - although not the smallest terns - at about 28cm long. Unfortunately they are classed as endangered, although there were good numbers of them around the pyramid.
This final, and rather cropped shot, shows a flock of these birds which managed to always stay just too far from the boat - although the picture does show the 'compact flocks dip and flutter over surface near breeding islands' that is also mentioned in my guide book.
And now you know what comes next - click the blue button and off you go.
As a special favour to me, could you try to think of 1 or 2 bloggers who would be able to post here and invite them along - it would be good to start 2016 with a bang! Cheers SM