I’m treading water in the Indian Ocean surrounded by an 80-strong swarm of snorkellers. We’re in the South Ari Atoll, at the site of a manta ray “cleaning station”. Alongside me, anxious swimmers thrash about in lifejackets, as numerous boats – I count 17 – idle nearby. Feeling uneasy, I dive down briefly, just in time to watch a lone manta escape the chaos of flailing limbs and GoPros. An unruly free-for-all, it’s a far cry from the magical encounter I’d dreamed of. Resurfacing with a sinking feeling, I head back to the boat. I’ve seen enough.