1. A two-person tent. Just for me. This leaves room for all my bits and bobs. Always buy a tent that sleeps more people than you actually want to sleep in it. I swear. Mine is a three-season tent from Sierra Designs that has stood up well to the occasional downpour and even a couple inches of snow on one memorable May morning. I like a vestibule so I can stash my shoes in it and keep my tent tidy inside.
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This little fella has done ok over the past four years, the zippers tend to stick but it's roomy and comes with a rain fly that works like a charm! Great for unexpected downpours! Also, it was on sale ;)
2. A good inflatable sleeping pad. I swear these are a worthwhile investment, which I am reminded of every time I pack up my tent and realize that I was sleeping on a pine cone all week. Mine is not the poofiest but I am more of a back sleeper and less of a side sleeper so I don't mind as much, if you are a devoted side sleeper a poofier pad is your best bet since your hip will be digging into it. But I had a non-inflatable foam pad early on and it just doesn't do the job.
3. A cozy sleeping bag. Nuff said.
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Edited To Add: after four years of hard use and infrequent washing, this sleeping bag has finally had a seam open up in an interior corner. It was a bitch to sew up as it was three-sided but I will see if it survives. The rest of the bag is in great shape.
4. Lighting options. I have a little flashlight that extends and makes a little lantern that I can hang from my tent ceiling. Normally I use a headlamp but when in a tent trying to take your contacts out a headlamp will make an unfortunate (and blinding) glare in your little travel mirror. So I have two lighting options that I travel with, and our crew has a bigger communal lantern that lives in the cooking area. It may attract bugs but can be helpful for late-night Cranium games when headlamps would blind your teammates.
We carry a lot of communal gear like folding tables and chairs and propane stoves that make life a little more comfortable out there. But these are my camping necessities. When I camp with Matt we take his VW bus so I don't need most of this stuff but I sure am glad to have it when I am out for a week at a time for work.
What are your camping necessities? Do you like to car camp, backpack or just stick to a nice hotel?