The inaugural TT Triathlon is underway with almost 100 taking part either as individuals or in teams of three.
The Douglas Bay swim started at 6am.
The short course competitors face a 1.2 mile swim, a 37.7 mile bike ride and a 6.5 mile run.
But that goes up to a 2.4 mile swim, 114 mile cycle and a 26.2 mile marathon run for those doing the full distance.
The Mountain Road, between Ramsey Hairpin and the Creg Ny Baa Hotel is closed between 7.30am and 3pm.
Race Director Richard Wallace says spectators will be made very welcome throughout the day: