The Massey Tunnel was the first structure in British Columbia built using immersed tube technology, and the method is worth picturing. The tunnel was not bored through the riverbed. It was cast on land in six precast concrete sections — each 344 feet long, 78 feet wide, and 24 feet high — which were then sealed, floated out onto the Fraser on barges, manoeuvred into position above a shallow trench dredged into the loose sand and silt of the river bottom, and sunk. Once the sections were joined, crews buried them: 500-pound stones filled fifty feet out on either side, with a bed of 1,500-pound stones laid over the top as armour against the river's scour. Construction began in March 1957 and cost roughly $16.6 million. The tunnel opened to traffic on 23 May 1959 as the Deas Island Tunnel, and Queen Elizabeth II came for the official ceremony on 15 July.

At its deepest, the roadway runs about 22 metres below sea level — the lowest road surface in the country, and the only road tunnel in Canada that goes beneath sea level at all. The tube itself is 629 metres long, a single structure divided down the middle by a concrete wall so that each side carries two lanes, joining Richmond on the north bank to Delta on the south. Ventilation and pumping machinery sits in a building at each end, and concrete retaining walls carry the approaches out roughly 400 metres. Five kilometres downstream, the Fraser finishes its journey and empties into the Strait of Georgia. Dangerous goods are barred from the tunnel, and there is a hard height limit of 4.15 metres — a number that a certain number of truck drivers rediscover the hard way every year.

There is a problem underneath. The tunnel was designed in the 1950s, when seismic engineering barely entered the calculation, and it sits on a layer of river sediment roughly 600 metres thick before anything like bedrock appears. In a major earthquake, that sediment could liquefy — behave momentarily like a fluid — leaving the structure with nothing beneath it. By the early 2000s the risk was well enough understood to act on, and a seismic retrofit ran from late 2004 to November 2006. Then came something more unusual. In 2009 an earthquake early warning system called Shakealarm was commissioned at the tunnel, the first commercial system of its kind installed to protect critical infrastructure anywhere in North America. It buys seconds to minutes. If a dangerous quake is inbound, gates at both portals close so that nobody else can enter, while anyone already inside drives out as normal.

The tunnel has been fighting its own capacity since almost the moment it opened. On 28 January 1981, a reversible lane system was introduced, part of a $2.5 million program that had already added a bus lane to the approaches. At peak hours, a line of swing gates squeezes one direction into a single lane and opens three lanes to the other — northbound into Vancouver in the morning, southbound out of it at night. Cyclists have had a harder time. It is illegal to ride or walk through the tunnel, so bikes depend on a fare-free shuttle that runs limited hours and carries seven at a time, or on TransLink buses whose two-bike racks fill up instantly during summer. Since this is the main route between Vancouver and the Tsawwassen ferry terminal, the bottleneck has been a long-running complaint. In June 2022 TransLink tried a Bike Bus with room for nine bicycles, running from late June to Labour Day between the ferry terminal and Bridgeport station.

Replacing the Massey Tunnel has consumed nearly two decades of provincial politics. A plan to widen it from four lanes to six surfaced in 2006. In 2012 the premier announced a full replacement within ten years, and by December 2015 the government had committed to a $3.5 billion bridge with associated interchange work. Metro Vancouver's mayors came out collectively against that bridge in June 2016 — the first time the board had opposed the project as a bloc — and asked Ottawa for a federal environmental review, which was declined in February 2017. Ground was broken in April 2017 amid protests. After the election that year, the incoming government scrapped the bridge and went back to consultation. In 2019 the mayors recommended a new eight-lane tunnel instead, and that plan received approval in August 2021. It is toll-free, includes pedestrian and bicycle facilities at last, carries a projected cost of $4.15 billion, and is scheduled to open in 2031.