SEATTLE — A dozen or so men and women, cinched into life jackets, paddles at the ready, were about to launch their kayaks into Elliott Bay early Thursday evening with Seattle’s glittering skyline as the backdrop. For some of the paddlers, it was a first-time experience, and with the water at 50 degrees and choppy, there were some obvious signs of trepidation.

“O.K., what hazards are we watching for?” Elizabeth Chiaravalli, their instructor, shouted, and a smattering of answers immediately bounced back. “The waves!” “The dock!” “The pilings!”

Then Cynthia Orr, 67, a mental health counselor, spoke up. “Shell Oil!” she cried, standing by her boat. Her fellow kayakers — or kayaktivists, as they call themselves — roared.

The standoff between Royal Dutch Shell, which proposes to lease a terminal in the Port of Seattle for its Arctic drilling fleet, and the opponents who want to block the company’s plans for environmental and other reasons, is going aquatic. The various groups organizing a “ShellNo Flotilla” for Saturday hope to attract 1,000 kayaks or other small boats, and are arranging temporary housing for people coming from elsewhere to train and participate.