A few kayakers were out while we were in Ballard. One group appeared to be either a club or a training course. Most of them were in identical looking kayaks while they seemed to be escorted by a pair of kayakers in more professional looking rigs. They did not go into the lock but came to check it out before heading back in the opposite direction.
Another pair came from the direction of Lake Union and were heading towards Puget Sound. They did take a ride through the lock. Since they did not have ropes to tie off during the lowering of the water, they hung on to one of the other boats as the water level was lowered before paddling out of the lock and on their way. I imagine being at the bottom of the lock in a kayak is quite intimidating but they seemed like seasoned users.