The other I knew would participate, as I've tied her as often the occasion allows and she loves it. They were both already prepared to swim so both were in their swimsuits at the time. My willing victim loves to play roles so we settled on a simple one for now, a simple burglar who breaks in and ties up the girl he finds alone.
She went into the kitchen and pretended she was just rummaging through the cupboards when I snuck up behind her and grabbed her and clasped a hand over her
mouth. "Mmmmmppphhh!" she squealed behind my hand as I dragged her over to the couch.
I forced her down onto her stomach and yanked her wrists behind her and used a cable tie to bind her wrists together. (We decided to experiment with an alternative to tape) I went out of character to ask if it wasn't too tight, she said it was fine before turning back into a whimpering victim, "What are you gonna do with me?"
I simply ignored her as I fixed her ankles with another cable tie, once again assuring I hadn't made it too tight. "Please, just let me go!" came her cry as she squirmed around.
I then took a strip of duct tape and placed it over her ready lips. She always does me the courtesy of shutting her mouth before the tape is applied.

She then began squirming and "Mmmmpppphhhh"ing for all she was worth like she was a real damsel-in-distress. I just sat back and enjoyed it all, occasionally leaning forward to slap her playfully on her butt or tickle her just to get a reaction from her helplessness.
After a short while I cut her loose and she beamed at me, happy that we were finally able to do this again. (It's been over a year since our last outing.)
Off topic we then went swimming, the two of them and their neighbor. Men were in the minority that day at the pool and most the time I had these three girls hanging onto me or I was playfully chasing and grabbing them in the water.
Also upon returning to their home and changing I also got a five minute session of holding her on my lap, handgagged.

So overall it was a dang nice day!
Call me a tease, but yes I do have pics/video of the session and no, I ain't up for sharing. Except for those who know who they are.......