Amazon has the YI Discovery Action Camera on sale right now for just $44.99 when you use the promo code YIDISCOV at checkout. That will take $15 off of the regular price and really make the YI Discovery Action Camera a pretty good option for those looking for an Action Camera capable of shooting 4K footage.
The YI Discovery Action Camera is a pretty sweet action camera to check out, seeing as it does do 4K at 20fps and is able to do 1080p at 60fps, so you're going to get some pretty good footage out of this one. It also has a 2-inch display so you can actually see what it is you are recording. YI is using a wide-angle lens on this one, so you can get even more into the shot. It does 150-degrees, which is enough to get plenty of subjects into the shot. There are eight shooting modes here and it is also waterproof, so you can go ahead and use this in the pool or at the beach and not worry about killing the camera. Of course, that is the reason why many would want an action camera anyways over a regular camera. Because it is able to do things that a DSLR can't do, and that includes going in the water and being dropped from time to time.
This item is also eligible for Amazon Prime's free shipping. Which includes free two-day shipping, and pretty cheap (usually $3.99) next-day shipping if you need it extra fast. If you are not an Amazon Prime member yet, you can sign up for a free trial of Amazon Prime. You'll get 30 days free (if you're a student, you get 6 months), and then it's $119/year (or $59/year for students). Prime members do get a whole lot more than just free shipping though, so be sure to check out the full benefits.