I am a pretty big geek, and I love to travel and take day trips. I am also someone who prefers to stay connected, be it for business purposes, or personal. When I’m out and about I use every downtime opportunity to get online. In many cases I don’t want to carry a bag with me when I’m out exploring, so I have to slim down to the bare essentials.
Here is my list of 4 absolute necessities that I carry when I plan to be out for an extended period. The idea here is that everything on this list is able to be carried in your pants pockets. Unless of course you prefer skinny jeans, then it might be a bit tight. These items probably won’t be enough for more than a day, but should be enough to get you through a full days adventure, and possibly even an overnighter.
Cell Phone (and Apps):
I know this one is pretty obvious, but it is really the only reason I can travel without a bag, so it’s worth the mention. I don’t just use my phone for the usual calls, pictures, music, and social media; I use it for literally everything. I keep mine loaded with a variety of applications to keep me informed, 
communicating, productive, and entertained. I even keep tools to monitor, manage, and post on my websites, as well as an SSH client for server management as needed. If used effectively, your smartphone can do pretty much any online task you need to accomplish, way more than 90 % of the population uses them for. Another thing I will do is before I go on my day trip I will download applications specific to the local attraction or area I will be visiting, and then delete them after I no longer have a use for them.
Phone Charger and USB Cable:
As I do use my phone for everything I find that I need to charge up more often than the average user. I always carry a small phone charger and cable with me. I use a 12W, dual-port charger , it’s not a certified
fast charger per say, but it does the job sufficiently. I recommend one with folding prongs, this will make it that much more compact. Many places will have outlets you can use, but if there are none easily accessible, I have no shame, I will ask a restaurant or bar if they have outlets I can plug into, they are usually happy to help out, just don’t forget to tip. It can also be used to charge the next item, a backup battery.
Backup Cellphone Battery
These devices are great; outlets are not always available, or are a bigger inconvenience than they are worth, so for me this is a must. These can charge your phone (or other USB devices) multiple times , or just provide power to keep you running during the dreaded low battery. They can also be used to charge devices for others if they came unprepared. I carry either my Kamashi 10,000mah or the even lighter Mopower 10,000mah unit. Both of these have proven reliable, and retail for under 20 bucks. Both are good for about 2.5 full charges of my Note 5, although I typically only use it to keep me running until I can find real power.
Dual connection USB Drive
As my phone stays pretty full with apps and music I also carry a USB drive that has both regular USB and micro USB connection options. This is an immensely useful tool as you can offload data from your phone, as long as it supports the drive, which most modern Android devices do, without eating up your data plan. This is especially important 
overseas, as I often have a local sim installed, and only buy the data I will need. These devices are great for if you take a lot of pictures or video. I keep a few movies or shows on it for those times when I find myself bored. I also keep a full suite my favorite portable apps and bookmarks for when I use a computer at a business center or internet café. The one I use is the Kingston 64GB, it hasn’t failed me yet, and is USB 3.0. A word of advice here is to not keep these loose in your pocket, they are small. I lost one already, so now it is on my key chain.
