I've had a kayak for about a year. I have two things to share. One is on attitude of safety. The other is why I arrived at my own boat choice in light of it. To the point, I think a yak can be even more safe than kicking out, especially if it's out far enough. And arriving rested even as I'm in good shape, makes the dive all the more a dream. But buddy up like you would diving.
I got cert'd in 1972, and to this day have no idea how anyone could dive (or yak for that matter) alone. What if you need help, or if alone for some reason aren't able to get on that spiffy radio? Not to ridicule having a radio, it's smart and I've already done some research - I'm about to buy one next week (or an epirb if I can justify spending 4x more). I currently carry an air horn, smoke/flares and a signal mirror, and twice the water I can drink, carabinered onto the boat by climbing strap, which is duct taped onto the bottles like river raft folks do.
I have taken the yak diving only in areas at the far edge that I would kick out to so far, just to be conservative this year. Because I tend to be conservative, and have a wife, I also bought (no kidding) a motor, thinking that if it got windy some time in a way I did not accurately enough plan for, I could tool back. (Yes, this model can take a motor on their custom mount). That's after once getting into a fight with the wind by way of learning, early in the process. I think the danger of kayaking is in thinking that it provides a false security.
If something hits the fan, could I kick home, or to a hospitable shore? That's where I'm at with attitude, so that enables me to feel that I can go even miles upshore or downshore, as long as I could do that in an emergency. Here on the CA Northcoast, it can be not exactly placid sometimes.
As for the motor, sorry to anyone who thinks that is whimpy or not "purist" enough. I thought that it would be so cool to be able to scoot back after a deep dive to exert less or not at all, or in a changing wind just in case my planning wasn't perfect. We all like to be perfect, but (at least I) (hope) that my planning will account for all things and changes, including current and wind. In my years of diving I've had more than my share of 'learning experiences' even when I thought I was being prepared and intelligent.
I got a Sevylor diveyak xk2020 inflatable last year. Built like a zodiak of kayaks ( big gunwales), at 3' wide and 13' long, I can sit on the gunwhale with a weight belt on, and can't even get the thing to tip 30 degrees. Amazingly stable. One reason for this choice was that I wanted not only to have the convenience of throwing it (and my buddy's, too!) like a suitcase into the trunk to have when I needed it...But also having tried a hardshell, I love how totally stable to tipping it is and how easy it is to reach and tie everything down on deck. Five separate chambers are reassuring, and the material is pretty strong. I think about the shark thing. Frankly, the last thing I'd love to do is hang around on the remaining one or two or three remaining chambers... But I think the thing is very safe. The label says don't go more than 1/4 mile offshore, but who would anyway diving. The thing paddles like a dream; sits on the water, not in it. I've paddled hard kayaks, and this one doesn't have the tip/lose your gear factor like they do, although I do tie everything down on the 20 tie-downs this thing has.
On the motor, it's nice to know that this little Minn-kota Riptide 40 salt water trolling motor (silent and no stink) is capable of chewing a 1,000 lb boat top speed (about 4.5mph) for 1.5 hours...or up to 8 hours at lowest speed (2/3 my own easy paddling speed). I'm 220 lb with gear, soaking wet. They told me my butt had better be solid in that boat when I click it on, or I'd better have a long line trailing, because it is instant-on. Yep, I made one of those too...of floating poly yellow rope. A kid's 4' foam float tube tied and washered at the end to see it. Yeah, you click on the speed, and it stays on. Now, I've owned this motor for a year, and have yet to try it out, because I want to have the feeling of being one with the boat (seaworthy) before I'd turn a motor into a crutch. So this has been my paddling kayak try out year. I'm about ready to try the motor and am very excited now to do so.
So that's it. Don't be stupid and have false security, and pick something comfortable and fun, and you'll have a ball!