If you look closely at the photo, you can see that the lower dolphins are essentially perpendicular to the camera. However, the airborne dolphin looks to be jumping toward (or away from - hard to tell as it's dark) the camera at maybe a 45 degree angle. Given that offset angle to the waterborne dolphins, if the sunlight is coming from the left or right side of the frame, it makes sense that the exposed side of the airborne dolphin could be in the shadows - so the apparent darkness is not a problem.
Further, from what I've read (and seen first hand), wild dolphins can jump up to 15-20 feet high (trained dolphins have jumped up to 30 feet). Below are 2 images from Tiputa Pass in Rangiroa (rough as heavily cropped from iPhone video frame grabs) - the first is as the dolphin breaks the surface and the second is as it reached the top of it's leap - lighting looks familiar, eh?
Further, from what I've read (and seen first hand), wild dolphins can jump up to 15-20 feet high (trained dolphins have jumped up to 30 feet). Below are 2 images from Tiputa Pass in Rangiroa (rough as heavily cropped from iPhone video frame grabs) - the first is as the dolphin breaks the surface and the second is as it reached the top of it's leap - lighting looks familiar, eh?
