A pee in the sea is a drop in the ocean | Letters

Andreas Swadlo, Andrew Wardrop and Tony Coghan respond to an etiquette guide saying swimmers must dash ashore rather than relieve themselves in the water

I have long been puzzled by the widespread belief that if nature calls while swimming in the sea, one should dash ashore in search of a lavatory (Summer etiquette: 47 essential rules – from sex to sunloungers to shopping in swimming trunks, 14 July). Why this is considered the more virtuous option escapes me. The contents of the lavatory are, after all, treated and eventually discharged into rivers and seas. The ocean merely cuts out the middleman.

Assuming one is well away from other bathers, the environmental distinction seems elusive. The Atlantic Ocean has the capacity to cope with a few hundred millilitres of highly diluted human urine. It has been dealing with whales for rather longer than it has with us.