Reuben Mellor-Clark, 21, was filmed surfing a tidal bore, where the sea pushes a wave up a river, part-way way back to his house from the beach in Perranporth, CornwallReuben Mellor-Clark, 21, was filmed surfing a tidal bore, where the sea pushes a wave up a river, part-way way back to his house from the beach in Perranporth, Cornwall