LONDON -- Twenty miles, 12 locks and two pints into our boat trip through central London, we needed a cozy place to moor for the night. We were motoring through the murky waters of Limehouse Cut, a small section of the vast canal network that striates the city, a metropolitan wasteland stretching before us. Foreboding brick warehouses, barbed-wire fences and graffiti murals lined the banks of the canal. The runners and bikers who had populated the bustling towpath throughout our weekend voyage had disappeared, and the landscape had taken a grittier turn.

“Are you sure we’re going the right way?” I asked my husband, Brian, who was at the helm of our 58-foot narrow boat, Carli.

“No,” he said, shooing away the map I was waving in his face.

We’d decided to venture into territory that was slightly off the map we’d been given at the marina, but we expected to reconnect with familiar waters at any minute. Slightly worried, I scanned the badlands, pockmarked with decommissioned smokestacks and abandoned buildings, for familiar landmarks: a bridge marker, a signpost, a spray-painted clue as to where we were headed. Nothing.

Then, from among the wreckage, a roller coaster appeared. Well, at first it looked like something plucked straight off the New Jersey boardwalk. But as we rounded the bend, we recognized the towering red jumble of metal, with a space-age observation deck held tight in its grip, as the controversial centerpiece of London’s Olympic park: Orbit tower. After Orbit, the sparkling tiara points of the Olympic Stadium came into view, and the rush of discovery invigorated my inner sailor.

Over three days of urban canal cruising, my family and I were experiencing something intoxicating: liquid London, an underworld of waterways, tunnels and locks coursing through some of the city’s most eclectic neighborhoods, from the quaint boathouses of Little Venice to $50 million mansions in Regent’s Park, through the hipster haven of Shoreditch and on to the Olympic zone in un-self-consciously cool Hackney Wick.

Few London sightseeing experiences are as unspoiled by crowds and commercialism as a ride in your own rented narrow boat. From the canals, you can hardly see any of the city’s iconic sights, such as Big Ben. Yes, you could arrange for a pilot to navigate the River Thames for a drive-by of London’s main attractions. But we enjoyed hiding away from the typical chaos associated with Big Bus Tours and delving deeper into London’s core. The long, skinny boat we rented was the perfect vessel for navigating centuries-old locks still operated by hand, allowing us to disembark at weekend markets, canalside pubs and lush parks.

My husband and I, with our 5- and 1-year-old daughters, had taken narrow boat trips through the British countryside before for a fresh-air-infused escape from the city. This time, however, we decided to splash down in the center of London for a weekend of urban saturation.

We began our recent voyage at the suburban outpost of Yeading, about 12 miles west of London. The London Ring, as the route we were going to follow is known, covers 44 miles along the Paddington Arm of the Grand Union Canal, the Regent’s Canal, Limehouse Basin and a short stretch of the Thames.

The scenery on the Grand Union started off bleak, with miles of housing blocks and factories interrupted by stretches of unkempt wilderness and the occasional waterside grocery store.