A gopro, some lense filters, and one of these and you'll be set. I've had this mount for a few years now and it's super helpful with getting good shots. Fits perfectly in the pocket of my BCD. Before I got it, motion sickness was just a side effect of watching my dive videos.
This is what I use for underwater (scuba) stuff. You can mount up to two lights to it, and you can even screw the entire thing onto a tripod if needed.
I’m all about starting cheap to find what I like and then upgrading to better stuff later once I master what I have. No sense spending lots of money on something to figure out you hate it. That said I just picked up this rig on amazon super cheap. It fits gopro and many other cameras.
Movo GB-U70 Underwater Diving Rig... https://www.amazon.com/dp/B0734772HY?ref=ppx_pop_mob_ap_share
I just ordered this one for diving and shooting on the boat.
https://www.leisurepro.com/p-bblvtl3800p/bigblue-vtl3800p-3800-lumens-video-tech-light
https://www.amazon.com/dp/B0734772HY/ref=cm_sw_r_sms_apa_i_j2dYDb57B8M15
https://www.amazon.com/dp/B00AHCUNG2/ref=cm_sw_r_sms_apa_i_e3dYDbAN09R48
https://www.amazon.com/dp/B07SCT8PTH/ref=cm_sw_r_sms_apa_i_N3dYDbB4ZDS5D
https://www.amazon.com/gp/product/B0734772HY/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
The mount is two separate parts. https://www.amazon.com/gp/product/B07HKKDD2D/ref=oh_aui_detailpage_o04_s01?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0796PVRXT/ref=oh_aui_detailpage_o04_s02?ie=UTF8&psc=1