I'm trying to understand why the quality of this picture isn't acceptable

Without any context, I’m not entirely sure what I’m looking at. In Stock photography, the subject should be obvious. For comparison in Stock inventory:

https://stock.adobe.com/search?k=dolphin

https://stock.adobe.com/search?k=manatee

https://stock.adobe.com/search?k=porpoise

https://stock.adobe.com/search?k=shark

https://stock.adobe.com/search?k=whale

Both seem a bit over-saturated and unfortunately just aren’t sharp enough. I just got back from a whale-watching trip and had to delete the majority of my images due to soft focus. It’s really challenging to get sharp images when the boat, the whale and the photographer are all in motion !

Composition could be improved. The main subject should take up a larger percentage of the image. Shutter speed too slow or the subjects are out of focus.