The country's Chamber of Diving & Water Sports announced the closures, in the South Sinai, as part of a plan to raise the standards both of dive centres and safari charter boats operating in its territory.
Decrees for the closures had been passed because the centres - one in Taba, eight in Dahab and 14 in Sharm el Sheikh - were said to have operated without a Ministry of Tourism licence for two years.
Alongside the licence-enforcement programme is an auditing process that was introduced in May last year. The aim is to check that centres and boats are "working to the same safety standards and offering tourists a high quality of service".
The standards are based on a suitably adapted version of certification administered by the European Underwater Federation.
Auditing for South Sinai was completed at the end of March, at which point firm decisions could be made as to whether centres could be granted licences or not. The closures were announced within a month.
Auditing for diving businesses in the Hurghada area is due to be completed by the end of July - leading, no doubt, to announcements of closures of any businesses failing to meet the standards now defined by the CDWS.