During Hull's teenage years in the Upper Cumberland hills, he often "ran the river" with Allen Gore, floating logs down the Caney Fork and Cumberland toward Nashville and taking a steamboat back.

CNN: Excerpt: 'The Prince of Tennessee: The Rise of Al Gore'

In places, the ground was so boggy the line had to be laid on a floating raft of logs, where it is still ironed flat by passing trains.

BBC: Full steam ahead

Crossing the great Atrato swamp, where the track became a causeway over slimy logs and then a mat of floating grass, the bike would sometimes sink into nothingness.

ECONOMIST: Ian Hibell