The billion dollar tunnel project at PortMiami is months from opening day, and when the work is completed, it will be the biggest port for cruise ships in the world.

A tour was given Tuesday of the tunnel that runs nearly a mile long and is 90 percent complete. It will connect PortMiami's Dodge Island to Watson Island.

The underwater underpass is about 42 feet in diameter and runs deep below Government Cut. At the shallow end, the tunnel buries itself 50 feet under the water; at the deep end, 120 feet below Biscayne Bay.

Although still a bit dark, workers were at the tail end of construction, putting on all the finishing touches, including installing the electrical grid.

Four years of hard labor have made the tunnel fireproof, waterproof, hurricane-proof. Four lanes of traffic -- two in each direction -- will allow vehicles direct access to the port from the highway.

“This port, Port Miami, will be one of the only ports in the world with a direct connection from the port to the highway without a single traffic signal," said Port Director Bill Johnson.

Johnson led the tour through the underground passage. State and local leaders, including Florida Attorney General Pam Bondi, joined him.

“We just cannot wait until the completion, and just think about everything it's bringing to Miami: 250,000 jobs," said Bondi.

Funded at the county, state and federal levels, this is one of the largest public and private projects in the country.

May 19, 2014 is the slated date for the official opening of the tunnel at PortMiami.