There's a tiny tip of sand at the very northern tip of New Zealand's southern island called Farewell Spit.

It is lovely and remote. It is also a graveyard for whales. Just this month some 200 pilot whales stranded themselves on farewell spit. At least two dozen died.

For reasons that have long puzzled scientists, whales can't resist the urge to beach themselves on Farewell's sands. Despite the best efforts of rescuers at least 680 whales have died there since records have been kept.

One theory is that the shallow waters around the spit somehow interfere with the whales' sense of direction.