It's not even May, but already signs of summer are upon us. The Delaware River Waterfront Corporation has announced newly expanded free summertime programming along the river — including the early opening of Spruce Street Harbor Park — on May 6.

The seasonal pop-up park — with its floating, landscaped barges and riverbank hammocks — has attracted more of the city's iconic restaurateurs. Kevin Sbraga, Chickie's and Pete's, and Franklin Fountain will be joining Jose Garces and Federal Donuts on the water.

Later, on Memorial Day weekend, the Blue Cross Riverink Summerfest — an outdoor roller rink on the water's edge — will open for the summer with a new mini-golf course designed by selected area artists. The lounge tent (the "warming hut" during the winter ice-skating season) will be converted into a crab shack operated by Chickie's and Pete's.

"This really has happened," said Pete Ciarrocchi, president of Chickie's and Pete's. "These pop-up beer gardens?  This is a pop-up on steroids. You've got Kevin Sbraga, Jose Garces, Franklin Fountain, Chickie's and Pete's, Federal Donuts. These are great Philadelphia icons in one space. Why wouldn't you want to be here?"

The new amenities are a testament to the success of the pop-up experiment, said Tom Corcoran, the president of the Delaware River Waterfront Corporation.

"When we first started, this is the third year, we were hoping for 100,000 people to come. We got 500,000. Last year was more," said Corcoran. "With the roller skating rink, it's taking off as well. You can feel the waterfront coming alive."

The seasonal park and roller rink have retained their primary sponsors — Valley Green Bank and Independence Blue Cross.

Corcoran said the concepts have enough flexibility to change in the future, so as not to get stale.