In your account Statistics the XP left for next level is actually showing 2 levels up.
I just leveled up to Sea Admiral at 19,000 XP. And it says I have 30,000 until the next level. But the Kraken level is at 36,000 XP, only 17,000 more.
Same for me, im at "Aye aye captain!" and it shows the exp for 2 levels ahead and not one level.
On my first level-up I got a notification that I'd reached the highest level. Sadly, it was not to be...