Organisers of the Tall Ships Race say they are on course to attract a million visitors to the four-day event in Hartlepool.
Just over 600,000 people have seen the armada of 59 vessels, which are berthed at the town's marina and Victoria Dock, Hartlepool Council has said.
A Tall Ships village has been created, which features live entertainment as well as craft and food stalls.
The event ends on Tuesday when all vessels take part in a parade of sail.
A spokeswoman for Hartlepool Council said: "An estimated 350,000 visitors flocked to the site on Sunday.
"The figure, up 100,000 on Saturday's 250,000 total, took visitor numbers for the first two days of the event beyond the half a million mark."
Mayor Stuart Drummond added: "We have had some fabulous feedback from people.
"The highlight of Sunday was undoubtedly the crew parade, a fabulous display involving all of the crews which was enjoyed by everyone.
"We are delighted with the way the whole event is going."
The Tall Ships Race takes place every summer in European waters.
Up to 6,000 young people from more than 30 countries take part, with at least half of each crew being made up of people aged between 15 and 25.