For anyone interested in swimming, I bought a Delphin Hydroactive today.
While (imo) swimming is the best cardio activity, swimming laps gets real boring and music is a must. Unfortunately, bluetooth and underwater streaming don't go together, making listening to music while swimming much harder. This device is like a miniature ipod shuffle that I can use my Amazon Music on, download a playlist, and swim (it's a miniature waterproof tablet). As opposed to an MP3 player, I can update the playlists easily with wifi. I'm pretty excited to see if it works as advertised.
I'll provide a review in a week or two.
I know you've all bookmarked Outlook for this one... Excellent tech recommendation here, for those that run outdoors you should pay attention too:
Aftershokz Xtrainerz
Amazing bone conduction headphones, they work on vibration so not actually inside your ears, they sit between your temple and the edge of your ear. Sound quality is excellent, but your ears are uncovered, so if you're running outdoors, you can hear your surroundings clearly too. Completely waterproof, feels like it is built well, and very comfortable. I've gone on 5 swims so far on the same charge, it is rated to 8 hours, feels like it should get there. I like using silicone molded ear plugs for swimming and hear music loud and crystal clear underwater, and again, so comfortable and easy to use (1 2 3).
Here are the cons; if you're attached to your phone, these aren't for you, it isn't bluetooth, strictly an MP3 player (the Delphin I purchased in the OP is sort of like a mini tablet, which I wish somehow this had the capabilities of). You load your music from your computer. My personal music source is Amazon Unlimited, which lets me take music offline, but only through their App, there are obviously no apps for an MP3, so I'm buying about 100 strictly workout songs that I'm loading directly into the unit (can hold 1,200 songs if you own a ton of music already, simple drag and drop operation here). It was about $100 cheaper than the Delphin, so that cost almost evens out for the 100 songs. I've found the interface and setting up folders doesn't work so well. In example, I connected it to a MacPro and erased the 4 songs that came preloaded on it in the folder, but they're still on the MP3, this should've erased those songs, but it hasn't. The files I uploaded can't rewind to the previous song either, I can only fast forward, need to solve that too.
Anyways, if you own a healthy amount of music and run outdoors, these are prob a good purchase if you can drop your phone for an hour. If you swim, you should 100% buy these - I swim almost an hour a day on these things and my body feels awesome after the pool, easily capable of taking on weight training afterwards. Personally, I found sticking a headphone into my ear underwater highly uncomfortable, but if it doesn't bother you, then the Delphin could work too, while having a better interface to control your music.