Following the Hunter accident - which is not the point of this thread - everyone seems to be climbing on the 'over sea' bandwagon for flying displays, but aren't we now increasing the safety risk for the aircrew involved.
On a nice clear day, with unlimited visibility, a bit of wind to give texture to the surface and a clearly defined coastline it can be fairly straightforward - and I mean no disrespect to those participating. However, start taking away some of those factors, particularly a smooth/calm sea with little wind allied with reduced visibility or full cloud cover and it becomes much harder to judge a lot of things. Turn away from the coastline and sudden disorientation can occur, a smooth sea can make the surface almost impossible to see (OK, gates and altimeters both rad and baro will help, but the Mk 1 eyeball can be fooled). Of note my worst case of disorientation occurred just in a gentle turn away from the coast at 100ft in what seemed like 'adequate' conditions for the demo in hand.
I would assume weather limits for over-water displays would have to be improved, and pilots/aircrew would have to practice a little more for that scenario.
AFAIK there have been no accidents so far at shoreline air displays due to weather (although as usual stand to be corrected), but would appreciate other views on the subject.