Downstream

gives a heavy sigh. ‘Stick to
swimming pools,’ he mutters.
We set off upstream
towards London Bridge,
while Martin gestures
repeatedly out of the window:
‘the tide is going out now, so
we’re going against it. Look
at the current around those
buoys.’ He wants me to
understand what would
happen to a swimmer in these
waters: ‘if you come up
against a barge or something