Floatswella — the pop-up paddle-craft-only rally formerly known as Floatchella and Float Ella — returns to the Mystic River on Saturday.

The event is a partnership between The Downtown Mystic Merchants, the Greater Mystic Chamber of Commerce and North Swell.

Here’s what happens: Folks can hop into their paddle craft and wend their way to an area north of the Mystic River drawbridge on the west side of the river. There, bands will play on a floating stage tethered to land near Gravel Street. This year’s reggae groups will include Red Lion, Natural Element and DJ Blade Mon.

Organizers say that lifejackets are required, and they ask that motorized vessels stay clear of the event. They are promoting these places as launch sites: under the I-95 highway bridge on River Road, on Isham Street, on Water Street across from the Daniel Packer Inne, and on Williams Beach at the Ocean Community YMCA, where volunteers will be available to assist people and accept donations for The Downtown Mystic Merchants and the Greater Mystic Chamber of Commerce.

Floatswella, 1-4 p.m. Saturday, Mystic River, north of the drawbridge; free; rain date Sunday; mysticchamber.org.