Headphones with offline storage

Hi everyone, new user here! I wondered if any of you have experience with offline-audio headphones.
I prefer listening to music while (trail)running without having to carry my phone with me. My Vertical does not have any offline storage like the Run does. So I looked around and found some headphones with offline storage, such as the Suunto aqua.
Personally I like the idea of them also beeing waterproof, though I never tried swimming with headphones...
So what can you say about the Suunto aqua? Are there any alternatives around? Did you have any connection-issues with the watch, especially while swimming?