Open water : swimming in lakes, sea or rivers
SwimEverything that is not a pool: no walls, no lane lines, no guaranteed flat water.
Three big differences from pool swimming: SIGHTING (every 6-10 strokes to hold the line), CONDITIONS (chop, current, water temperature, wetsuit) and PACK START (contact, surges). 70% of Ironman DNFs happen in the swim : usually because one of these three was underprepared.
In TriPaced:
TriPaced doesn't yet generate dedicated open water sessions (V2). In the meantime, add 2-3 real open water swims in the last 8 weeks before the A race and log them manually as "Z2 endurance".
Source Baldassarre R. et al., 2017 : Water Immersion and Swim Training Adaptations - Open-water competitors (Sports Medicine)