Open Water Swimming: From Pool to Open Water

6 Min. read

In the indoor pool you see the black line on the floor. In the lake you see nothing. No pool edge, no bottom, no end. Open‑water swimming is a completely different sport from lane swimming. And that’s exactly what makes it so intense. But: 393 people drowned in German waters in 2025. This guide shows you how to make the transition from the indoor pool to open water safely and correctly.

Sources: DLRG Statistics 2025, German Swimming Federation

Why open water is a different sport entirely

What is open water swimming? Open water swimming (German: Freiwasserschwimmen) means swimming in natural bodies of water like lakes, rivers, or the sea. Unlike lane swimming, there are no lines, no walls to push off from, and no visible bottom. Orientation relies entirely on sighting (head-up swimming) and external landmarks on shore.

In the pool, everything is controlled: 25 or 50 metres, constant temperature, clear water, the pool edge always within reach. Open water strips all that away. Water temperature fluctuates with depth and currents. Waves, wind, and limited visibility completely alter your swimming experience. Many swimmers who easily cover 2,000 metres in the pool panic after just 200 metres in a lake—not because of fitness, but because of psychology.

That’s no reason not to try it. It’s a reason to prepare properly. Open water swimming is one of the most intense nature experiences you can have in sport: you’re in the middle of a lake, the sky above you, darkness below, and all that matters is your next stroke. Those who embrace it—and who’ve already tried wild swimming—know what water does to the mind.

Cold Shock: What Happens to Your Body Below 15 Degrees

The most dangerous moment during open-water swimming isn’t exhaustion after 30 minutes. It’s the first 30 seconds. When water temperature drops below 15 degrees, your body reacts with so-called cold shock: uncontrollable inhalation, hyperventilation, and a sharp spike in heart rate. Being submerged in water under these conditions can be fatal.

The DLRG recorded 393 fatal drowning incidents in Germany in 2025. 88 percent occurred in freely accessible inland waters—the very places where open-water swimmers train. The causes are almost always the same: underestimating water temperature, overestimating one’s abilities, and swimming without supervision.

The solution: Enter the water slowly, never jump. Swim the first few meters deliberately and slowly. Those who master breathwork techniques have a real advantage here, as controlled breathing helps reduce the cold shock response. Above 18 degrees, cold shock is generally no longer an issue for most people. In April and May, German lakes typically range between 10 and 16 degrees. At that point, a wetsuit isn’t optional—it’s essential for survival.

Gear: What You Need to Get Started

The basic equipment for open-water swimming is more manageable than many think. Here are the essentials:

1. Swim buoy (€20 to €40): The most important accessory. This bright orange or pink buoy attaches to a waist belt and floats behind you. It makes you visible to boats and provides buoyancy to hold onto in an emergency. Its internal compartment allows you to store keys and your phone in a waterproof space. Never swim without a buoy.

2. Wetsuit (rental: €10 to €20/day, purchase: €80 to €250): Strongly recommended below 18 degrees water temperature. A 3/2mm suit (3mm on torso, 2mm on arms and legs) is sufficient for most German waters. Tip: Rent one at first. Many triathlon shops and swim clubs offer wetsuit rentals. This way, you can test different fits before investing.

3. Swim goggles (€15 to €35): Not pool goggles—choose a model with a wider field of vision. Tinted lenses for sunny conditions, clear ones for overcast skies. Polarized lenses significantly reduce glare from water reflections.

4. Swim cap (€5 to €10): Neon colors for maximum visibility. Silicone caps fit better than latex and offer slight thermal insulation. For cold-water swimming, consider a neoprene cap.

Technique: How Open-Water Swimming Changes Everything

Three things distinguish open-water technique from pool swimming:

Navigation (sighting): Every five to six strokes, briefly lift your head and look forward to check your direction—this is called sighting or crocodile swimming. Pick a fixed landmark on shore (a tree, building, church steeple) and align yourself with it regularly. In a pool, you swim straight because lane lines guide you. In open water, without correction, you’ll naturally swim in a curve.

Breathing: In the pool, you may breathe to one side only. In open water, you must be able to breathe on both sides, as waves and wind dictate where you can take a breath. Practice bilateral breathing (switching sides every three strokes) in the pool before venturing into open water. This is the most crucial preparation.

Rhythm: Without turns every 25 or 50 meters, the natural pause disappears. You swim continuously. This changes your rhythm and energy distribution. Start slower than you would in a pool. Swim the first 200 meters at a deliberately reduced pace, then ease into your normal rhythm. Anyone who goes full throttle from the start will be exhausted by 400 meters.

Five Rules for Safe Open Water Swimming

Rule 1: Never go alone. Always swim with a buddy or in a group. If you prefer training solo, stay parallel to the shore and no more than 50 metres away. A SUP companion is ideal—they can paddle alongside you and reach you immediately in an emergency.

Rule 2: Check the water first. Currents, depth, boat traffic, entry and exit points—get the lay of the land before you dive in. Lakes with DLRG supervision are perfect for beginners. Steer clear of rivers if you’re new; currents are often stronger than they appear.

Rule 3: Respect the water temperature. Below 15°C, only swim with a wetsuit and experience. Below 10°C is strictly for seasoned ice swimmers and extreme athletes. Water warms up slower than air—20°C outside can mean just 12°C in the water.

Rule 4: Always wear a tow float. No exceptions. Even if you’re only swimming 500 metres. Even if there’s not a boat in sight. Your tow float is your lifeline and your way to signal for help. In an emergency, you can hold onto it while waiting for assistance.

Rule 5: Get out before you have to. In a pool, you can stop at the edge. In open water, you’ve got to swim back. Plan your route so you cover no more than 70% of your usual pool distance. If you can do 1,500 metres in the pool, cap your open water swim at 1,000 metres. That buffer is there for the unexpected.

Open water swimming isn’t just pool swimming with a view. It’s a discipline all its own—with its own rules and risks. But if you prepare, take your gear seriously, and keep a healthy respect for the water, you’ll discover a sport that’s downright addictive. That first moment when you’re out in the middle of the lake, surrounded by nothing but water, sky, and the sound of your own breath? That’s when you’ll understand why open water swimmers never look back.

Source: Header image – Pexels / Thamyres Silva (px:20624585)