You know that simile about being a sardine in a tin? Rush hour on the Tube springs to mind: hot carriages, sweaty armpits, pushy bankers.
OK, you have to do it, but really, if there was a choice … no. So here I am, in the warm tropical waters of the Philippines, being part of the real thing, completely immersed in more sardines than you would have thought existed. There are so many the sunlight has been obliterated.
Just after dawn, I had rolled into the sea near Pescador Island and watched as a shadow materialised out in the blue. The shimmering grey shape rolled slowly towards the reef wall, transforming into the most immense ball of fish I have ever seen. Millions of tiny flashes of silver were huddled together in the mammoth fishy mob.
The school approached and surrounded me, cramming me into their invisible tin with no visible sign of escape. I hovered spellbound until they suddenly started to disperse. The tiny bodies dashed off in all directions as a gigantic tuna came barrelling in at speed, launching into the body of the sardine school and splitting it into myriad smaller groups. But as quickly as the school disbanded, the sardines regrouped into an even tighter ball, as if it had never happened.
The story goes that just a few years ago, the walls of Pescador were regarded simply as a beautiful dive – neither unusual nor unique. Then one day the sardines appeared from nowhere. They stayed long enough to attract all the relevant predators and capture the attention of local divers. Then, just as quickly as they came, they left.
A year later, the sardines reappeared in the same place and so far have remained. No one knows why the fish disappeared, where they went or even why they came back, but they are definitely there, proving the point that there are some creatures that actually do like to huddle like sardines in a tin.
Beth and Shaun Tierney run seafocus.com, a resource for scuba divers and are the authors of Footprint's 'Diving Southeast Asia'. (£19.99)