IP Ratings
IP ratings, short for "ingress protection ratings", tells the consumer how environmentally resistant an electrical component is. This is usually done through testing at a certified facility (for reputable manufacturers) or randomly chosen (for more sketchy manufacturers). This results in uncertainty over the reliability of a device's ingress protection. In short, do not look at IP ratings as the end all and be all.
ROVs constantly go beyond depths of the general consensus for IPx7 (submersion for 15-30 minutes at 1m depth). Thus, IPx7 or below is not safe for use without additional waterproofing measures. IPx8 poses a risk as well and also requires waterproofing modifications.
It is important to keep in mind that IP ratings are designed for waterproofing consumer electronics devices, such as people who drop phones in toilets or use headphones in the rain. IP ratings aren't designed for people making underwater robots.