New Trip Editorial Department　　Updated: 2026.05.19

Rainy Season Protection: How to Choose a Waterproof Suitcase and a Hands-on Review of New Trip

Title

Have you ever had these experiences on a business trip or vacation during the rainy season?

  • Your clothes or documents inside got damp from the humidity
  • When you arrived at the hotel, the surface of your suitcase was soaked, and it took time to wipe it dry
  • Water seeped in through the zipper, getting your important belongings wet

Rain during the rainy season is a major enemy for suitcases. However, many people mistakenly believe that "hard cases must be waterproof."

In fact, even hard cases are not completely waterproof.

Especially with zipper-type suitcases, water can easily penetrate through the zipper, and there is a risk of the contents getting wet when traveling in the rain.

[Rainy Season Suitcase Waterproofing Measures: Conclusion]

  • ✓ Zipperless (aluminum frame type) offers the highest waterproofness
  • ✓ Zipper-type requires a waterproof cover
  • ✓ PC material excels in water repellency
  • ✓ Dry within 24 hours after getting wet

This article thoroughly explains suitcase waterproofing measures for the rainy season.

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Contents

1. Main Causes and Risks of Suitcases Getting Wet During the Rainy Season

2. Actual Verification of New Trip 1101 during the Rainy Season

3. Key Points for Choosing a Waterproof Suitcase

4. Waterproofing Measures by Scenario (Business Trips, Family Trips, Solo Trips)

5. FAQ (Including Case Studies of Failures)

6. Summary

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一、梅雨にスーツケースが濡れる主な原因とリスク

Causes of Wet Suitcases

  • Water seepage from zippers
    Zippered suitcases have their greatest weakness in the zipper itself. Rainwater can seep through the gaps in the zipper, wetting the contents inside. The risk of water seepage is particularly high in moderate to heavy rain.
  • Splashing water from the bottom and wheels
    Roads are full of puddles on rainy days. When you pull a suitcase, the wheels splash water, wetting the bottom and sides. This is especially likely to happen on stairs at train stations or when getting in and out of taxis.

Risks of a Wet Suitcase

  • Damage to belongings: Business documents become unusable, clothes become unwearable, electronic devices malfunction
  • Deterioration of the suitcase itself: Mold grows on the interior, metal parts rust, zippers become difficult to move
  • Mold and odor due to humidity: During the rainy season, humidity is high, and leaving the suitcase as is can cause mold to grow
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二、実際に梅雨期に使って検証

1. 検証条件

Verification Model: New Trip 1101

  • Material: PC (Polycarbonate)
  • Construction: Aluminum frame (zipperless)
  • Size: Carry-on size

Verification Period and Weather

  • June 3, 2025: Moderate rain
  • June 10, 2025: Light rain
  • June 11, 2025: Light rain

Verification Area: Tokyo (travel around stations, airports, and city)

2. 雨の日の移動実測

June 3 (Moderate Rain)

When using the stairs and escalators at the station, there was a lot of splashing, and the surface of the suitcase got wet. However, the PC material had high water repellency, and water droplets bounced off like beads. Because of the aluminum frame structure, there was absolutely no water intrusion from the zipper area.

When getting in and out of a taxi, I placed the suitcase in a puddle by the roadside, but there was no water intrusion into the main body. The water droplets were removed just by wiping with a towel.

After walking for 15 minutes in the city, the surface of the suitcase was entirely wet, but upon checking the interior, the contents were completely dry. I truly felt the effectiveness of the zipperless design.

 

June 10 (Light Rain)

The surface was only lightly wet and dried quickly after wiping with a towel. There was no water intrusion into the interior. After arriving at the hotel, I turned on the air conditioner to air dry it, and the surface was completely dry in about 2 hours. This confirmed the quick-drying properties of the PC material.

 

June 11 (Light Rain)

It hardly got wet, and a light wipe with a towel was all that was needed.

3. ファスナーレス設計の防水性能

  • Benefit of no water penetration from the zipper area
    Over three days of testing, what we realized most was the high waterproofness of the zipperless design. With typical zippered suitcases, water can seep through the zipper area when moving for 15 minutes in moderate rain. However, the New Trip 1101, with its aluminum frame structure, has no zipper area, eliminating the risk of water penetration.
  • Waterproofness of the aluminum frame structure
    The aluminum frame is a structure that secures the opening and closing parts of the suitcase with a metal frame. Compared to zippers, there are fewer gaps, making it difficult for water to enter. Since it is made of metal, it is less prone to deterioration, and its high sealing performance when opening and closing is a distinctive feature.
  • Water resistance when fully loaded
    When a suitcase is fully loaded, internal pressure increases, and zippered types are more prone to developing gaps. However, the aluminum frame type maintains its seal even when fully loaded, so its waterproofness does not decrease. In fact, we moved it in moderate rain while fully loaded, and there was no water penetration inside whatsoever.

4. ファスナータイプとの比較・防水カバーの重要性

  • Zipper-type luggage: Infiltration risk
    During the verification period, we also tested zipper-type suitcases. After 15 minutes of travel in moderate rain, the zipper area was wet, raising concerns about water infiltration into the interior.
  • Effective use of waterproof covers
    When using a zipper-type suitcase, a waterproof cover is essential. Ideally, choose one that fits the suitcase's size, is made of a thick material (nylon, polyester), and can cover the bottom completely.
  • Cost-effective options
    　　Aluminum frame type (e.g., New Trip 1101): Higher initial cost, but no waterproof cover needed, making it more cost-effective in the long run.
    　　Zipper type + waterproof cover: Lower initial cost, but requires purchasing and managing a cover.

For those who travel frequently during the rainy season, the aluminum frame type is more practical.

New Trip 1101 防水スーツケース

アルミフレーム・防水スーツケース

New Trip 1101

Sサイズ・40L｜56x37.5x21.5cm｜3.8kg

PC素材 アルミフレーム ファスナーなし TSAロック ストッパー付きキャスター

¥25,980

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Title

三、防水スーツケースの選び方ポイント

1. 素材で選ぶ：ポリカーボネート vs ABS vs ソフト

Polycarbonate (PC)

  • Water Resistance: ★★★★★ (Highest)
  • Highly water-repellent, repels water. Lightweight and durable.
  • Ideal for the rainy season

ABS Resin

  • Water Resistance: ★★★☆☆ (Moderate)
  • Cheaper than PC, but slightly less water-repellent.
  • For those on a budget

Soft Case (Nylon/Polyester)

  • Water Resistance: ★★☆☆☆ (Low)
  • The fabric itself absorbs water easily and is slow to dry.
  • Not suitable for the rainy season

Conclusion: If water resistance during the rainy season is a priority, polycarbonate (PC) material is the best choice.

2. 構造で選ぶ：ファスナーレス vs ファスナータイプ

Zipperless (Aluminum Frame Type)

  • Waterproofness: ★★★★★
  • Pros: No risk of water ingress from the zipper, high sealing performance
  • Cons: Slightly heavier, higher price
  • Recommended for those who prioritize waterproofness above all else

Zipper Type

  • Waterproofness: ★★☆☆☆ (★★★★☆ with waterproof cover)
  • Pros: Lightweight, inexpensive, expandable features can be added
  • Cons: Prone to water ingress from the zipper
  • Practical when used with a waterproof cover

Conclusion: If waterproofness is your top priority, choose the Zipperless (Aluminum Frame Type). If you want to keep costs down, opt for the Zipper Type + Waterproof Cover.

3. 防水ファスナー・防水加工の有無

If you're choosing a zippered type, check the following:

Water-repellent zippers (waterproof zippers)

  • Designed to minimize gaps in the zipper
  • Not completely waterproof, but reduces the risk of water penetration

Waterproof treatment

  • Water-repellent coating applied to the surface
  • Water droplets bead up and dry quickly

Note: Even if it says "waterproof zipper," it is not completely waterproof. For moderate to heavy rain, using a rain cover is essential.

Precautions when expanding a suitcase with an expansion feature

  • It is safer not to expand on rainy days.
  • If you do expand, always use a rain cover.

4. 重量・耐久性とのバランス

The higher the waterproof rating, the more the weight tends to increase.

Weight Guidelines

  • Carry-on size: 2.5–4kg
  • Checked size (medium): 4–6kg

Balancing Act

  • For frequent travelers: Prioritize lightweight luggage and supplement with a rain cover.
  • For those who prioritize waterproofing: Choose an aluminum frame type, even if it's a bit heavier.
New Trip 1101 防水スーツケース

アルミフレーム・防水スーツケース

New Trip 1101

Sサイズ・40L｜56x37.5x21.5cm｜3.8kg

PC素材 アルミフレーム ファスナーなし TSAロック ストッパー付きキャスター

¥25,980

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Title

四、シーン別の防水対策（出張・家族旅行・一人旅行）

1. 出張（ビジネスウェア・書類を守る方法）

Waterproof Packing for Business Wear

  • Suit: Place in a garment bag, then wrap the garment bag in a plastic bag.
  • Shirts: Place in a compression bag and remove air (for both waterproofing and wrinkle prevention).
  • Shoes: Place in a waterproof bag (to prevent wet shoes from touching other luggage).

Waterproofing Documents and Electronics

  • Documents: Place in an A4 size Ziploc bag, or use a clear file + plastic bag for double waterproofing.
  • Laptops/Tablets: Place in a dedicated waterproof case, or use a large Ziploc bag as an alternative.
  • Chargers/Cables: Place in a small Ziploc bag.

Travel Tips for Business Trips

  • When getting in and out of a taxi, do not place your suitcase in puddles.
  • When using stairs at the station, lift your suitcase.
  • On days with heavy rain, a rain cover is essential.

2. 家族旅行

Moisture Control for Children's Belongings

  • Change of clothes: Place each day's clothes in a separate plastic bag (makes it easier to separate wet clothes)
  • Diapers: Put them in a compression bag to save space (also offers waterproofing)
  • Toys/Picture books: Put them in a Ziploc bag for waterproofing

Rain Preparedness for Family Trips

  • Bring children's raincoats and boots
  • Adults should manage the suitcases and attach rain covers
  • Prepare extra plastic bags for wet clothes

3. 一人旅行

Minimum Waterproofing Measures

When traveling alone, it's best to minimize your luggage. We recommend the following waterproofing measures:

  • Several Ziploc bags: For separating important items (documents, electronics, clothes)
  • One absorbent towel: For quickly wiping a wet suitcase
  • Rain cover: Choose a compact, packable type

Tips for Traveling Alone

  • On rainy days, choose a route that shortens travel time.
  • Actively use taxis to reduce walking.
  • Upon arrival at the hotel, immediately dry your suitcase.
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五、よくある質問（FAQ）

Q1. 完全防水のスーツケースはありますか？

A1：完全防水のスーツケースは存在しません。

ハードケースでも、開閉部分（ファスナーやフレーム）から水が浸入する可能性があります。最も防水性が高いのはアルミフレーム式（ファスナーレス）ですが、それでも長時間の豪雨では浸水リスクがあります。

防水性を高めるには、レインカバーの併用が必須です。

Q2. ハードケースなのに水が入った、なぜ？

A2：ハードケースでも、以下の部分から水が浸入します：

  • ・ファスナー部分：最も浸水しやすい箇所。防水ファスナーでも完全には防げない
  • ・開閉部分の隙間：フレーム式でも、隙間から水が入ることがある
  • ・車輪・底面：水跳ねで濡れ、隙間から浸入する

中雨以上の雨では、レインカバーを使用しましょう。

Q3. レインカバー vs 本体防水、どっちがいい？

A3：両方の組み合わせが最強です。

本体防水（アルミフレーム式）：日常的な小雨には対応できる
レインカバー：中雨以上の雨や長時間の移動に必須

予算に余裕があれば、アルミフレーム式 + レインカバーの組み合わせが理想です。予算を抑えたい場合は、ファスナータイプ + レインカバーでも十分実用的です。

Q4. 拡張時の防水性は落ちますか？

A4：はい、拡張時は防水性が大幅に低下します。

拡張ファスナーは通常のファスナーより隙間が大きく、水が浸入しやすくなります。雨の日は拡張しない方が安全です。どうしても拡張する必要がある場合は、必ずレインカバーを使用してください。

Q5. 濡れたスーツケースのメンテナンス方法は？

A5：以下の手順でメンテナンスしてください：

1. すぐに拭く：吸水タオルで表面の水滴を拭き取る
2. 乾燥させる：スーツケースを開けて、風通しの良い場所に24時間以上置く
3. 内部を掃除：掃除機で砂や汚れを吸い取る
4. 車輪・ファスナーをチェック：動きが悪ければ潤滑剤を使用
5. 防水スプレーを再塗布：撥水効果が落ちている場合

カビを防ぐため、完全に乾燥させてから収納してください。

Title

六、まとめ

Rainy Season Suitcase Waterproofing: 3 Key Points

  1. Zipperless (aluminum frame) is highly recommended
  2. Zippered types require a waterproof cover
  3. Dry thoroughly within 24 hours after getting wet

New Trip 1101 provides peace of mind during the rainy season
The New Trip 1101 (PC material + aluminum frame) offers excellent waterproofing, especially during the rainy season.

In a real-world test, there was no water intrusion into the interior even after 15 minutes of travel in moderate rain.

For business trips and travel during the rainy season, choose a highly waterproof suitcase for a comfortable journey.

New Trip 1101 防水スーツケース

アルミフレーム・防水スーツケース

New Trip 1101

Sサイズ・40L｜56x37.5x21.5cm｜3.8kg

PC素材 アルミフレーム ファスナーなし TSAロック ストッパー付きキャスター

¥25,980

商品を見る

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