"Yeah! I have no idea how easy it is to get scuba gear here, but in the mean time I could always send you a video so you can at least see it!"

He figures that's still better than nothing, and he can keep an eye out for scuba gear for her in the mean time. He's never heard the term 'scuba' before, but he has seen it before, and it doesn't take much to figure out that the weird bodysuit that humans can wear to breathe underwater is probably what she means.