Noonsite is pretty good with background stuff.
Saudi Arabia is a very conservative Muslim country, difficult to visit by foreigners, except Muslims on a pilgrimage to Mecca. In order to preserve religious purity, tourism is actively discouraged. This includes cruising yachts.
A few yachts which have been forced to call at a Saudi port have been treated courteously, once the authorities have ascertained that the stop has been caused by a genuine emergency. Yachts that have either strayed into Saudi waters or have been apprehended cruising the offlying Farasan Islands without permission, have been escorted into port and detained for a few days before being allowed to go on their way.
Anyone intending to sail to Saudi Arabia must approach the authorities in advance to obtain the necessary permission. Otherwise it is better to avoid its waters, unless one is forced to make an emergency stop there.
Many areas of the Gulf are highly sensitive, including near maritime boundaries and the islands of Abu Musa and the Tunbs in the southern Gulf. Vessels entering these areas have been detained and inspected; there have been occasional arrests. Mariners should make careful enquiries before entering these waters or considering visiting ports.
So prearranging permission would be a must.
Doing something they don't understand may be interesting too.