First Ultra 100km, What should I pack?

I. 1st Ultra Marath
on 100km

I joined my first ultra marathon last weekend, from Saturday 5 p.m. to Sunday 9 a.m.

I had tons of worries before the race:

• What exactly should I bring?
• How much should I carry while running?

A senior runner in my club — he has completed 18 ultras and we call him “Haneul” — told me exactly what to pack.

If I hadn’t followed his advice, I probably would have dropped out halfway.

Here is everything I learned, step by step.

II. Organizer’s Phone Number & Whether You Should Drive

If you decide to drop out during an ultra, you call the organizer, stay where you are, and a car will come to pick you up.

Before the race, save the organizer’s phone number on your phone.

I also asked Haneul whether I should bring my car or use public transportation.

“If I drop out in the middle of the night, there’s no subway or bus… Should I bring my car?”

“Absolutely not! You’ll fall asleep at the wheel. I brought my car once years ago — huge mistake.”

“Then should I just wait?”

“Of course. Don’t even think about driving after an ultra.”

On the subway after the race, I kept nodding off without realizing it.

Do NOT bring your car to your first ultra.

III. Safety Light vs. Flashlight

I heard that a runner had once been hit by a car during an ultra, so I made sure to prepare visibility gear.

Many runners carried red baton-style lights, but they had several downsides:

• Too bulky inside a running backpack
• Many batons died around 4 a.m. due to low battery
• Holding two (front & back visibility) while running is unrealistic
• 
  
  
  
  

I used two small LED safety lights instead.

• One clipped to the back of my pack
• One attached to my arm
• Lightweight, easy to attach, long-lasting
• Bright enough until sunrise

Some runners used flashlights or headlamps, but about 90% did not. I ran with only moonlight and streetlights — and it was fine.

IV. Windbreaker, Rain Poncho, and Spare Clothes

A windbreaker and a rain poncho are essential. A spare set of clothes is extremely helpful.

You stop for 20–30 minutes around the 50km mark for food.

Sweaty clothes can drain your body heat very quickly.

• Change into dry clothes + dry socks at the half point
• Wear a windbreaker while eating
• Once you warm up again, pack the windbreaker

If you get injured and need to walk later, your body temperature will drop again — the windbreaker becomes essential.

I hesitated about packing a rain poncho because of the bulk, but if I hadn’t brought it, I would have been in danger.

During the final 10km — when I could only walk due to IT band and ankle pain — the rain began pouring.

Without the poncho, I would have started shivering heavily.

Even if the forecast says clear skies, always pack a poncho.

V. Smartwatch, Garmin, and Fuel

You don’t need to bring too much food.

Every 10km, the CPs provide rice cakes, simple meals, and drinks.

But 10km can feel much longer than expected.

You may get thirsty or lose energy midway.

I sweat a lot, so I stopped at convenience stores twice for drinks and energy bars.

I recommend bringing about 10 gels and a 300ml bottle to refill at each CP.

I used a Galaxy Watch — the battery died at 80km.

The last 20km were extremely hard because I couldn’t see the remaining distance.

If you use a Galaxy watch, please check battery life in advance.

VI. Pain Relief Spray

I used cooling spray on my knees at every CP — it helped a lot.

But by the time I reached 80km, the CP had run out.

Bring your own small spray bottle.

VII. What Each 10km Felt Like

This was my first 100km, and my running club supported me through messages.

I recorded a short video every 10km and wrote down my thoughts afterward.

Twice, I sped up too much — both times it immediately led to pain. Ultra running punishes carelessness.

(Korean) Ultra Marathon 104km: My Full Race Story →

VIII. Beginner-Friendly Checklist for Your First Ultra

If you’re preparing for your first ultra and feel overwhelmed, here is a checklist based on my own 100km experience.

1) Before the Race

• Study the course map, CP locations, and cut-off times
• Save the organizer’s phone number
• Share your expected route/time with family or friends
• Do NOT bring your car (extreme fatigue = danger)
• Practice night running at least 1–2 times
• Complete at least one 40km+ long run

2) Gear & Clothing

• Well-broken-in running shoes + extra socks
• Spare clothes for the 50km point
• Windbreaker + rain poncho
• Two LED safety lights
• Running backpack or waist pack
• One small pain relief spray

3) Fuel & Hydration

• 8–10 gels
• 300ml soft flask (refill at each CP)
• 1–2 convenience-store energy bars
• Electrolytes or salt tablets

4) Tracking & Safety

• Check your watch’s battery life
• Set low-power GPS mode in advance
• Fully charge your phone
• ID and emergency contact info

5) Condition & Mindset

• Stabilize your sleep schedule 3 days before the race
• No alcohol or heavy food the night before
• No over-pace for the first 40km
• Walk when you need to — walking is strategy
• Set pre-defined “stop criteria” (pain, dizziness)

Ultra running is less about speed and more about preparation, temperature control, and mental stability.

I hope this checklist helps beginners feel more prepared and finish safely.