Jenny Poulton, 33, makes a raised garden bed on the top of her boat in Roydon. Photo / José Sarmento Matos, for The Washington PostJenny Poulton, 33, makes a raised garden bed on the top of her boat in Roydon. Photo / José Sarmento Matos, for The Washington Post

Boats line Regent's Canal in front of Broadway Market in the Hackney district of London. Photo / José Sarmento Matos, for The Washington PostBoats line Regent’s Canal in front of Broadway Market in the Hackney district of London. Photo / José Sarmento Matos, for The Washington Post

Jojo Case, 37, bought a blue narrowboat last year for about US$36,000. Photo / José Sarmento Matos, for The Washington PostJojo Case, 37, bought a blue narrowboat last year for about US$36,000. Photo / José Sarmento Matos, for The Washington Post