There is no triathlon mode because they are not marketing or advertising it as a triathlon watch. TomTom specifically chose not to go after triathlons with this watch in the interest of attracting a wider audience who cross trains in multiple sports (the fact that the three sports happen to be in the triathlon is coincidence, not intent, they are the three most common non-team fitness activities). The TomTom lineup was never intended to be a triathlon watch and in the almost 3 years they have been out no triathlon features have been added so it does not appear they are going to change this. It was intended to be a MultiSport to allow users to train for the individual activities. It does not have open water swim, so it really would not work well anyway. If you want a watch that does full triathlons with transitions, etc. you will need to purchase one of the higher priced models from another company designed and advertised for that purpose.