What is this tube along the right side of a Blue Angel?
The aircraft is the A4 Skyhawk and the probe is for air-to-air refueling.



As you can see, it doesn't really impede the pilot's view which in any case, is concentrated on the refueller.

You can always spot a refuelling probe. For NATO aircraft, and most others, they always have the same tip and are the only appendages which look like this.

The Blue Angels used it since transits to various air shows exceeded the range and air-air refuelling is cheaper and more effective than landing, refuelling and taking off again.