Keith Stewart found that the loch goes to a depth of 889ft (270.9m) on sonar equipment he uses.
The official maximum depth on the current chart for Loch Ness is 754ft (229.8m).
But the Maritime and Coastguard Agency (MCA), which is responsible for the official measurements, said it has no plans to resurvey the loch.
Mr Stewart's discovery has been dubbed a new hiding place for the loch's mythical monster, Nessie.
The MCA is responsible for mapping the sea and deep lochs and lakes around the UK.
It does this in order to maintain British Admiralty charts under the UK Civil Hydrography Programme.
An MCA spokeswoman said: "We currently have no plans to resurvey Loch Ness."

The victim suffered serious injuries - believed to be stab wounds - after he was attacked at a house in Auld Coal Grove, Bonnyrigg, at about 16:00 on Tuesday.
He was taken to the Royal Infirmary of Edinburgh, where he later died.
The arrested man is due to appear at Edinburgh Sheriff Court on Thursday.

The Conservatives want a report into the spending on the 218 "procurement cards" used for government spending.
A further £475,540 was spent in the first three months of 2015/16.
A review was conducted in April 2014, but Welsh ministers said they do not publish the results of internal audits.
However, all internal audits are shared with the public spending watchdog, the Wales Audit Office.
Welsh Conservative leader Andrew RT Davies said: "Unfortunately, the minister [Finance Minister Jane Hutt] is refusing to publish that report, which leaves a number of questions unanswered: is the taxpayer getting value for money?"
The Tories say they would encourage public bodies to publish all spending of more than £500.
A Welsh government spokesman said: "During the audit process for the Welsh government annual accounts, the Wales Audit Office has the opportunity to review all of the Welsh government's financial transactions.
"If Mr Davies is suggesting that civil servants are improperly using procurement cards then he should raise his concerns with the permanent secretary."
A tour boat skipper has recorded a new deepest point in Loch Ness on his vessel's equipment.
[NEXT_CONCEPT]
A 36-year-old man has been charged with murder following the death of a 40-year-old man in Midlothian.
[NEXT_CONCEPT]
More than £3.8m has been spent in the last three years by civil servants using Welsh government-issued credit cards, prompting calls to reveal what the money has been spent on.