The elite unit was set up in 1978 and in the wake of the September 11, 2001, attack on New York, joined a European Union counter terrorism network called Atlas.
And yesterday, other members of the Atlas network, such as elite counter terrorism units from Denmark, Germany, Holland, Sweden, Belgium and France also took part in the storming of the passenger ferry and the release of hostages which were being held by armed terrorists.
The Atlas network is made up of 32 counter terrorism units from across the European Union and they are broken down into four tactical groups; naval, air, buildings and terrestrial transport.
Since 2005, the naval tactical group has stepped up its training and carries out an average of five exercises per year, be they in Northern European waters or in the Mediterranean. Since the Special Intervention Unit was created, it has carried out over 360 operations. It has freed over 560 captives and made 640 arrests, 141 of those being members of the Basque separatist group ETA.
The unit has also been involved in a number of major narcotics operations.