As mentioned all of the internet since CMOS took over CCDs as the "standard" sensor for the video market, there are a couple usual problems a rolling shutter may have underwater:
1. Strobe light capture can mess up exposure duration, so you get partial frames of different exposures. If you dive alone without "pesky" strobe shooters, it's not a problem.
2. fast movements by camera. Jerky motion like what you'd see on cellphone videos is a rolling shutter issue, but the newer CMOS sensors have reined in that distortion quite while. Since it's not that easy to move the housing that quickly underwater, it's not usually an issue. However, it is possible to induce it if you really try hard. Same for subjects which move very fast. I've used CMOS on bullet like tuna and if there is any RSE, it's negligible.
There are other issues like high gain switch noise effect, but that's usually more for smaller sensors than S35 and more.