The Special Air Service teams will use high-speed rigid inflatable boats to avoid traffic and increase their response speed.
The special forces troopers have been training for months against the potential threat of a Mumbai-style attack, in which terrorists seize hotels or other civilian targets and defend them against the authorities.
A source told The Sun newspaper: “All scenarios are being anticipated. London will be protected like never before – and the message is clear: if anyone is fool enough to try to endanger the public at these Games they will be met with the swiftest retribution by the best equipped troops of our most elite fighting units.
“Troops can deploy by air and water and be on site in moments. Then you’ve got force on the ground while the situation is monitored by the air.
Source: Andy Bloxham for telegraph.co.uk.