A horn blares as a small tug boat guides a large container ship leaving the port from downtown Vancouver towards the open sea. It's a common sight, as are the boats waiting just outside Vancouver's harbour in English Bay.

A tug boat guides the Ever Ultra container ship clear of the docks. (David Horemans / CBC)

The Port of Vancouver is the largest in Canada, making it an important nexus for trade and the country's economy.

But despite the heavy marine traffic and its enviable location in the downtown core, the port is often separated from the city it's a part of. Increased security after 9/11 means access to the port is tightly controlled.

CBC got an insider's view of the action.

Hastings-Sunrise houses over looking the port's container storage area. (David Horemans / CBC)

A busy port

It might look quiet from the distance, but up close the port is usually humming with activity.

A worker oversees the loading of train cars at the Port of Vancouver. (David Horemans / CBC)

The port handled 138 million tonnes of cargo in 2015, valued at $200 billion. And with 27 marine cargo terminals shipping a diverse portfolio from automobiles to grain and containers, the traffic going in and out can be quite hectic.

A loading crane descends into the hold of a boat. (David Horemans / CBC)

The port is also home to many marine animals, like these seals that like to sunbathe near the docks.

A baby seal suns on a log at the Port of Vancouver's debris pen. Harbour patrol clears the debris to keep shipping lanes clear. (David Horemans / CBC)

The port authority

For Kevin Ball, it's the smaller boats that are usually more concerning.

"Especially in the summertime, you've got all the pleasure boaters out who are not aware of the rules of the road," the senior harbour patrol officer said.

"Sometimes you see them heading towards one of the larger ships, and the captain can't see past those giant containers. You think he should be able to see you, but it's much further than you think."

Senior harbour patrol officer Kevin Ball steers his port authority vessel past one of the terminals. (David Horemans / CBC)

Ball and other harbour patrol officers are out on the waters almost 24/7, scouring for anything that looks out of place.

A tug passes by the Kinder Morgan docks on the north shore of the port. (David Horemans / CBC)

Traffic control

The port authority manages over 16,000 hectares of water, more than 1,000 hectares of land and approximately 350 kilometres of shoreline.

To manage all of that, the port has almost 400 cameras the operations centre can tap into.

Inside the port's operation centre at Canada Place in downtown Vancouver. (David Horemans / CBC)

It also monitors by GPS the location, speed and wait times of every truck and ship over 350 tonnes.

A truck passes by some of the many containers that it tows on a daily basis at Vancouver's port. (David Horemans/CBC)

Andriy Tereshchenko, one of the operations coordinators, says the ship traffic can also produce some interesting challenges.

"Sometimes there can be an interesting calculation that you have to make when you have a large vessel coming under the Lions Gate Bridge, and you have to see if it has enough clearance, figure out when the tide is right."

Two bulk carriers pass under the Lions Gate Bridge heading towards Vancouver's inner harbour. (David Horemans / CBC)

All ships coming in and out of Burrard Inlet are piloted by a B.C.-trained coast pilot all the way to when the ships move past Victoria.

"They are specifically trained for these waters," Ball says.