These work well:

https://www.ebay.com/itm/Camping-Hiking-LED-Waterproof-Light-Tent-Lantern-Outdoor-Emergency-Flashlight/383215848030?epid=24024316358&hash=item593971ca5e:g:PLoAAOSwC-5dp9bv

There are likely multiple sellers with essentially the same design. Look carefully as there are also ones that are two 18650s long as well.

It is a ?polycarbonate tube with caps on each end. As you screw the cap down it pinches an o ring that seals it to make it waterproof. I am not really a modder, but these things are completely simple to take apart and mod.

I bought a couple and they came with a 2000 mah 18650 which is soldered in place. I bought a couple of Panasonic 3400 mah 18650s with tabs soldered on and replaced the oricginal battery. They work well.

The don’t give 360 degree illumination, maybe a little more than 180 degree as the battery is on the back side, but are light, waterproof, and compact.

This one has better pictures to see what you are getting and comes with a 2600 mah battery for quite a bit more:

http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=113483595784&category=168867&pm=1&ds=0&t=1569288776000&ver=0&cspheader=1

On mine one press comes on low white then it cycles through high white red and I think blinking modes but at any time a long press turns it off without going through all the modes.

Here are the batteries I put in them:

https://www.ebay.com/itm/2-NEW-PANASONIC-NCR-18650-B-Li-ion-BATTERY-3400mAh-3-7v-w-pre-welded-TABS/371386465607?epid=1337918909&hash=item56785bbd47:g:YSQAAOSwDNdVqKwW