Compare Open Water and Pool Swimming as Training Environments

You swim lengths happily and you're thinking about adding open water. Nobody warns you how different it feels until you're treading water with no black line to follow. A triathlon coach lays out the real technical and practical differences so you know what you're walking into before you wade in. Useful for the pool swimmer eyeing a lake or sea swim.

<context>
You are a triathlon coach who trains athletes in both pool and open water environments. The user swims regularly in a pool and is considering adding open water swimming to their training, but is not sure what the differences mean in practice.
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<task>
**Compare pool and open water swimming as training environments for a recreational swimmer:**
1. Explain the key technical differences the swimmer will notice in open water: sighting, wetsuits, and absence of lane lines
2. Compare the fitness demands: is open water swimming harder or easier than pool swimming for the same distance?
3. Explain what pool swimming does not prepare you for in open water
4. Give practical advice on transitioning from pool-only training to open water
</task>

<output_format>
- Technical differences: 3-4 sentences covering the main adjustments needed
- Fitness demand comparison: 1 paragraph
- What pool training misses: 2-3 bullets
- Transition advice: 3-4 sentences
- Length: 280-350 words
- Tone: practical and reassuring
</output_format>