The only recompression chamber available to divers in the Republic has been closed due to HSE concerns that it does not meet international standards.
The chamber at University Hospital Galway will be replaced, but will not be ready for service for another nine months.
A recompression chamber is the only way to treat divers suffering from decompression sickness, commonly known as "the bends". Without the Galway chamber, divers in difficulty will have to be flown to the North to Carrickfergus, Co Antrim, or the Isle of Man.
The only other recompression chambers in the Republic are one at the Naval base at Haulbowline in Cork, which is closed to the public and at private facilities which are not used by the emergency services.
According to the Irish Underwater Council, there are about 40 diving incidents every year involving its members, of whom eight to 10 would require recompression treatment.
A council spokesperson said the closure would have a "huge effect", particularly as the chamber would be out of use for the entire diving season, March to September.
Irish Water Safety CEO John Leech said he was very disappointed to hear that the "essential life-saving device serving the entire west coast" was to be closed down.
While he welcomed news that the chamber was to be replaced, he expressed his concern that divers would be endangered by the distance to the next nearest public chamber.
A HSE West spokeswoman said: "Hospital management have notified the Coast Guard, Irish Underwater Council and ambulance control that the hyperbaric chamber service has been temporarily suspended. The current facility has reached its end of its life cycle and no longer meets international recompression facility standards.
"Galway University Hospitals have received approval from the Health Service Executive for the provision of a new hyperbaric chamber, the construction of which starts this month with an expected completion date of September 2008."
She acknowledged "the significant contribution and support of all personnel, particularly the anaesthetic consultants and volunteers from the Galway Sub Aqua Club to providing this service".
The chamber has been in operation for almost 30 years, with the aid of the Galway Sub Aqua Club, which provides technical support for its operation. A representative of the club declined to comment, saying the facility was owned and run by the HSE.