Virtual Reality - this is how it works
Download the free Polar Sea App to your Smartphone.
Choose the video and switch the VR mode on. The VR-Button is in the player on the right bottom.
Slip your phone inside a VR Holder or Cardboard.
Here you may find where to get VR Holder or Cardboard or try to build one on your own:
Try the DIY-version for a Cardboard
Tablets are too big to slip into a cardboard.