Open Water Swim: 2km Continuous Effort

Session Overview

This 45-minute open water session develops the aerobic capacity and mental composure needed to swim 1.9km (70.3) confidently. Swimming 2km continuously in open water is a landmark achievement for intermediate triathletes — it proves you can hold pace and rhythm without pool walls to push off. Complete this session in a safe, lifeguard-supervised open water venue wearing your wetsuit.

What You’ll Need

• Wetsuit (or swimskin if water is warm)
• Bright swim buoy for safety — mandatory for open water solo swimming
• Goggles with anti-fog treatment
• GPS watch with open water swim mode (optional but recommended)
• Lifeguard-supervised or safety-kayak-supported venue

Warm-Up (10 minutes)

Enter the water gently and spend the first 5 minutes acclimatising to the temperature — this is especially important in UK open water where temperatures may be 10 to 14 degrees in early spring. Swim easy freestyle for 400m, focusing on relaxed breathing and sighting every 8 to 10 strokes. Shake out your arms briefly and reset before the main set.

Main Set

The goal is to complete 2km continuously at an aerobic effort — conversational pace if you could speak. This is not a time trial; it is a sustained endurance swim that builds your aerobic base and open water confidence simultaneously.

• 2km continuous freestyle at Zone 2 effort (6 to 7 out of 10 perceived effort)
• Sight every 8 strokes minimum — pick a fixed landmark on the far shore
• Breathe bilaterally (alternate sides) for the first half to promote balanced stroke mechanics
• If you need to pause, stop and tread water for 20 seconds rather than standing — practice maintaining open water composure

Cool-Down (5 minutes)

Swim an easy 200m using backstroke or side stroke. Exit the water carefully, remove your wetsuit quickly to avoid overheating, and wrap up warm. Drink 500ml of water and eat a light snack within 20 minutes of finishing.

Coaching Notes

• If 2km continuous feels too ambitious, break it into 4 x 500m with 60-second rests and build to continuous over subsequent weeks.
• Common mistake: starting too fast. Your first 400m should feel almost too easy — you have 1.6km still to go.
• Sighting drill: lift eyes just above water level (not your full head) to see your landmark, then return to normal stroke. Lifting your head too high creates drag and disrupts your kick.
• RPE target: 6 to 7 out of 10. If you are above 8, slow down — this session is about time on task, not speed.