I carried a standard 20-liter daypack through three European trips before I finally admitted it was working against me. Getting into a crowded Barcelona metro car felt like a negotiation. Unzipping the back panel on a bus in Lisbon required me to take the whole thing off, spin it around, and hold up six people behind me. The bag was perfectly fine. The situation was not.
Switching to an RFID crossbody sling changed how city days feel. The WATERFLY RFID Crossbody Sling Bag is the specific bag I've been using since, and it earns its 4.5 stars from 47,000-plus buyers for reasons that are actually practical, not just aesthetic. Here are the 10 that matter most.
Your passport and cards are sitting in a zip-up bag on your back. Anyone behind you knows it.
The WATERFLY RFID Sling Bag moves everything to your front, blocks card-skimming signals, and costs under $35. Over 47,000 travelers have already made the switch.
Amazon Check Today's Price on Amazon →Your valuables are in front of you, not behind you
The single biggest security upgrade a daypack cannot offer: everything you care about is visible and reachable from your chest. On the WATERFLY sling, the main compartment and card pockets all face forward. No one behind you on a metro car can access your bag without you knowing. This is the reason most travelers make the switch in the first place, and it holds up in practice every single time.
RFID blocking keeps your cards safe from digital pickpockets
RFID skimmers are real, and they do not require physical contact. Someone with a reader can capture your credit card data through a bag just by standing close enough. The WATERFLY sling has a dedicated RFID-blocking pocket that shields contactless cards and passports from scanning. A regular daypack has no such protection. In transit hubs and busy city centers, that difference matters.
You never have to take it off to get something out
This sounds small until you are standing at a ticket kiosk, coffee in one hand, needing your phone or card. With a daypack you have two choices: set it on a surface that may not exist, or do an awkward shoulder shimmy to swing it around front. With the WATERFLY sling you just reach for the front zip. No stopping. No setting down. No creating an opportunity for someone else.
It fits in overhead bins without counting as a second bag
Airlines are increasingly strict about personal items. The WATERFLY sling bag is compact enough to slide under the seat in front of you on most aircraft, which means it does not compete with your carry-on for overhead bin space. On budget carriers where a second bag means a fee at the gate, the slim sling profile saves you the conversation entirely.
The crossbody strap distributes weight without shoulder strain
A daypack splits weight evenly across both shoulders, which sounds ideal, but on a light city day carry you rarely have enough weight to need both straps. The result is a bag flopping loosely on one shoulder all afternoon. The WATERFLY's single diagonal strap sits across the chest and stays put. The bag rests flat against your torso and does not swing or shift when you move through a crowd.
The first time I spun my daypack to the front at a Madrid checkpoint, I realized how automatically I had been announcing my valuables to everyone behind me for years.
It fits a day's worth of gear without the bulk
The WATERFLY holds a phone, slim wallet, passport, folding umbrella, a light jacket, earbuds, a snack, and a small water bottle. That covers most city day trips without needing to manage a full-size daypack. The organized interior keeps things from shifting, so you are not fishing around for your transit card at the bottom of a 20-liter bag.
Crowded transit is no longer a problem
On a packed metro, a daypack makes you wide. You bump into people, you block the aisle, and you have a large unmonitored surface directly behind you at hip level, exactly where experienced pickpockets work. The slim profile of the WATERFLY sling means you can stand in a crowded car without dominating the space around you, and everything stays in front where you can feel it.
The price does not require a commitment
At $32.99, the WATERFLY costs less than most daypacks worth buying. If you try the crossbody sling style and decide it is not for you, you have not lost much. But the 47,000-plus ratings suggest most people who try it do not go back. The value-to-protection ratio here is difficult to match at any price point.
It works as a personal item, a day bag, and a hiking pack
The WATERFLY is marketed as a sling bag, but the padded back panel and chest strap make it comfortable on short hikes too. I have worn it on coastal trails in Portugal and through airport terminals in the same trip. A standard daypack handles hiking fine but becomes unwieldy in urban settings. The WATERFLY handles both without needing you to swap bags.
You arrive at your destination with your card still in your pocket
This is the reason that matters most. RFID skimming incidents at high-traffic tourist areas are not rare. The WATERFLY's shielded pocket is a simple layer of protection that requires no behavior change on your end. You do not have to remember to do anything differently. You just put your cards in the right pocket, and the bag handles the rest every time you are in range of a scanner.
What I'd Skip
The WATERFLY is not the bag for a full travel day where you are moving between airports and hotels with checked luggage. The main compartment is intentionally compact, which is a feature for city days but a limitation when you need to carry a laptop, a full change of clothes, or more than one pair of shoes. For longer haul-days with a lot of gear, a structured daypack or carry-on is still the right call. The WATERFLY is a city and transit bag. It does that job exceptionally well. For everything else, you would need something bigger. For a deeper look at the bag's strengths and tradeoffs across nine months of real travel, see our full WATERFLY sling bag review.
At $32.99, the WATERFLY asks very little of you. What it gives back is the ability to move through crowded cities without carrying an anxiety tax on your back.
Stop making your passport easy to access for everyone except you.
The WATERFLY RFID Sling Bag is compact, front-access, and built to move with you through the most crowded travel days. One bag, no daypack anxiety. Check today's price and color options.
Amazon Check Today's Price on Amazon →