The only all-female crewed ship in the world was the first tall ship to sail into Halifax harbour on Tuesday, kicking off the 2012 Tall Ships Festival.

The Unicorn is one of more than 20 ships expected to stop in Halifax harbour in the next few days, attracting thousands of visitors to the waterfront.

The ship left Boston on Saturday and arrived in Halifax through thick fog.

The crew, including half a dozen teen girls, sailed through the fog and into the harbour.The crew, including half a dozen teen girls, sailed through the fog and into the harbour. (CBC)

For this trip, there are half a dozen teenaged girls on board, learning how to sail and life skills with the Sisters Under Sail program.

The program's founder, Dawn Santamaria said dropping boys from the equation means girls feel more comfortable dropping self-esteem and image issues.

"When there are no little boys around, that issue is non-existent," she said, "And those girls just blossom, right before my very eyes, and that's why I do this summer, after summer, after summer."

"They have the ability to come and go ahead and do it first and not let the fellas get in the way and take over," First Mate Hannah Imrie said, "So it provides a unique environment for them."

The Unicorn was also here three years ago during the last Tall Ships Festival in 2009.

This year, there are half as many ships as there were in 2009. But Colin MacLean, president of Waterfront Development Corp., said there will be enough land-based activities to keep people entertained.

"Parks Canada has given us Georges Island to open up to the public," MacLean said. "On Sunday, you can actually buy ...a modest ticket and take a family trip over to Georges Island, which is not something you can get to often."

The rest of the ships will be arriving over the next few days, many open for public boarding.

There will be several events this weekend, including events commemorating the 200th anniversary of the War of 1812.

MacLean said he expects the economic spinoffs will amount to about $32 million with about 94,000 visitors for the HRM.

The festival officially kicks off on Thursday and runs through Monday.