The Government has been notified of 11 "near misses" involving ships since the Rena disaster.
Foreign tankers and passenger ships were among vessels involved.
Between the Rena's grounding in the Bay of Plenty a year ago and late last month, Maritime New Zealand was told of two near misses involving passenger vessels, four involving container vessels, two involving tanker vessels, two involving cargo vessels and one involving a bulk carrier vessel. All the ships were foreign-owned.
A near-miss is defined as any incident where a crash was avoided by luck or recovery.
The numbers, provided to the Green Party by Transport Minister Gerry Brownlee, come amid renewed calls for compulsory shipping lanes for New Zealand - a concept backed by the disgraced captain of the Rena.
The Government has previously ruled out lanes, saying they are expensive to set up and police.
But one shipping expert, who told the Herald he had tracked dozens of ships sailing dangerously close to the coast, said having a better system was a "open and shut case".
Marico Marine senior partner John Riding believed that although the Rena disaster had been a warning, ship captains had become complacent again.
"Shipping is returning to its old ways," he said.
"The big furore is over, and the ships are still coming too close to land."
Mr Riding had noted this happening almost every two days.
The most common event was ships cutting too close when sailing to and from ports.
"We also tracked a passenger vessel - a cruise liner 280m long and capable of carrying 2500 people - going straight through the Mercury Islands, and so close to Mercury Rock that they were probably navigating beyond the accuracy of the charts."
He felt the need for a compulsory GPS-routing system was "bleedingly obvious".
"Do we need to look at a routing system around New Zealand? It's a black and white case."
Green MP Gareth Hughes accused the Government of "downplaying" the risk of further incidents such as the Rena disaster, saying it was not focusing on how to make coastal shipping safer.
"With the number of near misses since the Rena, it appears the Government is relying on luck, rather than good regulation to keep us safe from cargo ship crashes," he said.
He believed the issue should have been addressed in a review Maritime New Zealand is making of its response to the Rena disaster.
Labour also believed compulsory shipping lanes should be seriously considered.
Transport Ministry officials have told the Herald compulsory shipping lanes do not guarantee compliance with regulations or prevent navigational errors.
They said New Zealand already had guidelines for coastal navigation and a range of navigation technology to ensure safe passage and enable ships to be tracked.