Yes, you could sit down to watch Planet Earth II without donning headgear, but the two companies are betting that the advantages of VR will make all the difference. It's not just that you're engrossed in situations that would be difficult or impossible to record on camera -- it's that you're an "active participant" rather than a mere bystander. If all goes well, you'll have a better understanding of the aquatic ecosystem than you would by watching an ordinary documentary.