Can you hide from bees in a lake? This short video explains what happens if, while being chased by a swarm, one jumps into deep water to escape. The short answer is no.
Unfortunately, bees will be able to locate you and will wait for you at the edge of the water, or above your "hiding" spot. When you come up for air, the bees will swoop in to attack. This could make things even worse if you're trying to swim and fight off the bees at the same time.
The best way to survive a bee attack is to stay calm and try not to run or move your arms around in the air. This will only aggravate the bees more. Cover your face with your shirt if possible, and keep moving at a steady pace towards shelter. Avoiding floral scents and bright clothing can also help prevent bees from following you in the first place.
See also: Bees That Drink Human Tears