Each sport had very different requirements, even between water sports they don't translate across.

My parent got a concussion surfing, was wearing a kayaking helmet because that's what he has.

The kayak helmet is thicker than a surf helmet and contains more buoyancy.

When his head it the water it slowed down to quickly because the helmet couldn't penetrate fast enough.

Concussion was fairly serious and is still in recovery 4 years later.