Open Water Swimming Safety Guide: Dealing with Currents, Water Temperature, and Visibility

Open water swimming is the first leg of a triathlon and the segment that causes the most fear among athletes. The comfort of the pool disappears once you enter open water—you can’t see the bottom, waves hit your face, and people are all around you. This article will help triathletes swim confidently and safely in open water from a safety perspective.

The Three Major Risk Factors in Open Water

1. Tides and Currents

Understanding Tides

Taiwan is surrounded by sea, and swimming in coastal waters requires an understanding of tides:

• Flood tide: Seawater advances toward the shore; swimming with the flood tide toward shore requires less effort
• Ebb tide: Seawater recedes toward the open sea; the risk of rip currents increases during ebb tide
• Slack tide: The brief calm period between flood and ebb tides; this is the best time for water practice

Reference tool: The Central Weather Administration’s “Tide Forecast” website provides tide times for ports across Taiwan.

Identifying and Responding to Rip Currents

Rip currents are one of the most dangerous factors in open water, with flow speeds reaching 2-3 m/s—faster than Olympic swimmers.

How to identify them:

• A narrow, elongated area on the surface that is calmer and has no waves (a “gap” between whitecaps)
• A banded area where the water is darker or murkier
• Floating debris drifting outward on the surface

Response strategies:

• Never fight it head-on: Do not try to swim directly back to shore
• Swim parallel to the shore: Swim left or right to escape the rip current’s range (usually 10-30 meters wide)
• Relax and float: If you lack the strength to swim sideways, relax and float on your back; the rip current will weaken 50-100 meters offshore
• Raise your hand for help: A single raised hand is the international water rescue signal

River Swimming Considerations

Some triathlon events in Taiwan are held in rivers (such as the Keelung River and Xiuguluan River):

• Understand the river’s flow direction and speed
• The start direction is usually designed to go downstream or across
• Watch for underwater currents and eddies (especially near bridge piers and bends)

2. Water Temperature

Taiwan Water Temperature Reference

Month	Northern Coastal Waters	Southern Coastal Waters	Freshwater Lakes
Jan-Feb	16-19°C	21-24°C	14-18°C
Mar-Apr	19-23°C	24-26°C	18-22°C
May-Jun	24-27°C	27-29°C	23-26°C
Jul-Sep	27-30°C	28-30°C	26-29°C
Oct-Dec	21-26°C	24-27°C	19-24°C

Risks of Cold Water

• Below 18°C: A wetsuit is recommended; otherwise, hypothermia symptoms may appear within 20-30 minutes
• Below 15°C: Even with a wetsuit, swimming time should not exceed 30-45 minutes
• Cold water shock response: When suddenly entering cold water, the body involuntarily gasps and hyperventilates. Before entering, splash cold water on your face and neck to acclimatize

Wetsuit Selection and Use

• Full Suit: Recommended for water temperatures below 20°C; thickness 3-5mm
• Sleeveless: Suitable for water temperatures of 20-24°C; provides warmth without restricting shoulder movement
• Buoyancy benefit: Wetsuits provide approximately 5-10% additional buoyancy, reducing kicking energy expenditure
• IRONMAN rules: Wetsuits are prohibited when water temperature exceeds 24.5°C (age-group athletes); the threshold for professional athletes is 21.9°C

3. Visibility

Underwater Visibility

Visibility in open water can range from tens of meters (clear seas) to nearly zero (murky river mouths):

• Clear waters (such as Green Island, Orchid Island, and Xiaoliuqiu): Visibility of 10-30 meters; you can see the underwater environment
• Typical coastal waters (such as Taitung and Kenting): Visibility of 3-8 meters
• Murky waters (such as river mouths and harbors): Visibility of 0-1 meters; you cannot see ahead at all

Psychological Challenges of Low Visibility

Not being able to see the bottom is the main reason many pool swimmers fear open water. Coping methods:

• Focus on your stroke technique: Direct your attention to technical execution rather than what’s below
• Sight regularly: Look up every 6-8 strokes to spot the buoy ahead or landmarks on shore
• Drafting strategy: Find a swimmer of similar pace and stay about 1 meter behind their feet, using their wake to reduce drag
• Flip to backstroke in an emergency: If panic strikes, roll onto your back, float, look at the sky, and take 10 deep breaths

Surface Visibility

• Glare: When starting in the morning, the low sun hits the water surface directly, making buoys completely invisible. Practice sighting using buildings or mountain silhouettes on shore
• Wave conditions: When waves exceed 30 cm in height, sight at the crest of the wave rather than in the trough
• Fog: Fog frequently forms on lake surfaces in Taiwan on winter mornings, severely reducing visibility. Confirm the bearing of the turnaround buoy before the race

Safety Equipment Checklist

Essential Equipment

Equipment	Purpose	Recommended Brand/Specification
Goggles (two pairs)	One spare pair in case they get kicked off during the race	Wide-angle mirrored lenses for open water
Bright-colored swim cap	Increase visibility on the surface	Orange or fluorescent yellow silicone cap
Wetsuit	Warmth and buoyancy	Choose full/sleeveless based on water temperature
Swim buoy (for training)	Provides buoyancy in emergencies and increases visibility to others	Inflatable, worn around the waist
Sunscreen	Prevents sunburn (especially on the back of the neck and shoulders)	Waterproof SPF50+

Optional Equipment

• Waterproof earplugs: Prevent outer ear infections (recommended for those who frequently swim in murky water)
• Vaseline/anti-chafe balm: Apply to the neck, armpits, and inner thighs to prevent chafing from wetsuit friction
• GPS watch: Records swim route and pace; some models support open water mode

Self-Rescue Techniques

Technique 1: Cramp Management

The most common emergency in open water. Common sites: calves, soles of the feet, and hamstrings.

Steps:

1. Stop swimming and switch to floating on your back or treading water
2. Stretch the cramped area (for calf cramps: grab your toes and pull them toward your body)
3. Massage the cramped muscle
4. After recovery, continue at a slower pace, or switch to breaststroke/sidestroke

Technique 2: Panic Attack Management

Panic in open water is real and common. Symptoms: rapid breathing, accelerated heart rate, feeling like you’re about to drown.

Steps:

1. Stop swimming: This is the most important first step
2. Flip onto your back: Face the sky, spread your body into an X shape
3. Slow breathing: Inhale through the nose for 4 seconds, exhale through the mouth for 6 seconds, repeat 10 times
4. Self-talk: “I am safe, the water will hold me up, I can stop at any time”
5. Assess: After regaining calm, decide whether to continue or signal for help

Technique 3: Treading Water While Awaiting Rescue

If you are exhausted and cannot continue swimming:

1. Transition to an upright treading water position
2. Use slight sculling motions with your hands to keep your head above water
3. Raise one hand high to signal lifeguards
4. If you have a swim buoy, hold onto it and float on your back while waiting for rescue

Recommended Open Water Training Locations in Taiwan

Northern Taiwan

1. Feitsui Bay (Wanli)

• Type: Bay
• Water temperature: 24-29°C from May to September
• Features: Gentle wave conditions within the bay; multiple triathlon events are held here
• Note: Crowded on summer weekends; practice in the morning instead

2. Longdong Bay (Gongliao)

• Type: Bay/rocky coast
• Water temperature: 25-29°C from June to September
• Features: Clear water with good visibility; natural rock walls block waves
• Note: Water temperature is low outside the swimming season; a wetsuit is required

Central

3. Sun Moon Lake

• Type: Freshwater lake
• Water temperature: 22-28°C from May to October
• Features: Famous venue for the mass swim across the lake; calm surface suitable for long-distance practice
• Notes: Be aware of boat lanes; a tow buoy is recommended

Southern

4. Dapeng Bay (Pingtung)

• Type: Lagoon
• Water temperature: 22-30°C year-round
• Features: Enclosed water body with no waves or currents; best suited for athletes trying open water for the first time
• Notes: Moderate water visibility

5. Huoshui Lake (Taitung)

• Type: Artificial lake
• Water temperature: 20-28°C year-round
• Features: Swim venue for the Taitung Ironman; 800 meters long and 200 meters wide
• Notes: Stable water quality in an artificial lake; one of the safest practice environments

Eastern

6. Liyu Lake (Hualien)

• Type: Freshwater lake
• Water temperature: 22-27°C from May to October
• Features: Beautiful surroundings and open water surface
• Notes: Confirm whether open water activities are permitted

Open Water Training Plan

Transition from Pool to Open Water (8 Weeks)

Week	Training Content	Goal
1-2	Pool practice of bilateral breathing and head-up sighting	Technical preparation
3	First open water session, swim 10-15 minutes in a safe area	Adapt to the environment
4	20 minutes in open water, practice sighting and swimming in a straight line	Build confidence
5	30 minutes in open water, add drafting practice	Simulate race conditions
6	40 minutes in open water, simulate a group swim start	Adapt to physical contact
7	Simulate race distance in open water	Pacing practice
8	Easy open water swim + pre-race mental preparation	Build self-confidence

Safety Checklist for Every Open Water Session

• Check the weather forecast and tide times for the water body
• Have at least one companion or a shore-based observer
• Carry a tow buoy
• Inform others of your training plan and expected return time
• Ensure your phone is accessible on shore
• Know the location of the nearest medical facility

Safety is always the top priority. The risks of open water swimming can be greatly reduced through knowledge, equipment, and practice. When you have sufficient understanding of and respect for the water environment, you will be able to confidently face the swim leg of any triathlon.

Related Reading

• Triathlon Swim Training: Overcoming Fear of Open Water and Improving Efficiency
• Open Water Swimming Safety Guidelines: Buddy System, Current Reading, and Emergency Response
• Conquering Waves and Currents: Open Water Adaptation Skills for Triathletes
• Open Water Triathlon Swim Start Strategies: Crowd Conflict Management and Sighting Techniques