In the US, a waiver of liability for "negligence" for foreseeable actions regarding Scuba will typically be upheld. OTOH, a waiver for "gross negligence" may well NOT be upheld (that is definitely going to be jurisdiction specific). Were I the attorney writing the release, unless I was sure that my jurisdiction permitted waivers for "gross negligence" I would delete the reference for fear a Court might strike the whole thing down for being overly broad.
BTW, I once was a practicing attorney -- and I do get a chuckle out of people who give their opinions after writing they didn't "study the law."
BTW, I once was a practicing attorney -- and I do get a chuckle out of people who give their opinions after writing they didn't "study the law."