Little eight or nine footer. It is fun to use for exploring coves, but I wouldn't take it on open water. It doesn't offer the same king of exercise benefits as rowing, though. Rowing can be a great aerobic workout. Paddling can help with upper body but not much else.
In these parts, we call kayakers speed bumps. A group of them is a rumble strip. Some of the paddlers are skillful and safety conscious -- particularly those who are with instructors from one of the local paddling schools. Then there are those who are absolutely clueless; those are the ones that scare me.
There are a few simple things kayakers can do to be safe. Brightly colored paddle blades help tremendously in terms of visibility (mine are bright yellow, and my kayak is red). Groups paddling as a cluster is far preferable to them spreading out all over the place; one big target is easier to see and avoid than a whole bunch of little ones. But that cluster should stay out of the channel and instead keep close to shore. This should not be a problem since they draw only a few inches of water.
A little common sense goes a long way.