However, Destination Queenstown chief executive Graham Budd says the operators are a ''small subset'' of all adventure tourism operators in the resort, most of whom are covered by maritime and civil aviation regulations.
Operators offering activities that ''deliberately expose participants to a risk of serious harm'' must be independently audited by December 1 in order to be registered by WorkSafe NZ.
In October, the Government extended the deadline by a month to give more operators time to comply.
WorkSafe NZ senior communications adviser Joe Wallace said that of 18 Queenstown operators required to be registered, 10 had done so and four were undergoing the audit process.
Of the remaining four, three were ''planning to cease operating or are putting their business on hold'' while they decided whether to enter the process, and one operator had not been in contact with the agency.
Because the auditors were independent, WorkSafe NZ did not know how many operators would make the cut until the 5pm deadline, Mr Wallace said.
Mr Budd said he was not concerned by the ''relatively small number'' of businesses likely to miss the deadline, as most of the resort's major operators were covered by maritime or civil aviation regulations.
The cost of the auditing and registration process might have been too much for ''small, niche or part-time businesses'', or they had decided to stop operating as a result of ''natural business attrition''.
''I think anyone coming to Queenstown can be totally confident that they won't be turning up to any operation or activity next week that isn't fully regulated and covered under either existing or these new regulations.''
The regulations arose from a review of the sector ordered by Prime Minister John Key in 2009 after a series of fatal accidents.
Mr Wallace said if WorkSafe NZ was satisfied an operator had met its audit requirements, it would be registered by December 12.
An audited but unregistered operator could not legally operate after Monday until they were registered, unless they had been granted an extension.
Inspectors would be visiting operators throughout the country to enforce the regulations, he said.
Despite the rush by some operators to meet the deadline, the audits were to ''international standards''.
Nationwide, of the 347 operators required to register, only 174 had done so by yesterday.
