DOLPHINSSSSSSS!!! They're so cute. Admission: Adult $22, children 4-12 $17. They close at 5. They are located by the pool of Mirage. If you see Nectar, it's right outside.
You could finish this place in about 30 minutes so think wisely if you want to pay for admission (I used myVegas points for this). Dolphin feeding is every 15 and 45 minutes I think. They feed and the dolphins will do some flips, waves, etc. You can also see them more clearly at the underground viewing area. Pretty neat. In the back, there are lions, tigers, and leopards. Gift shops are pretty reasonable price. Picked up a cute little souvenir. Good way to pass some time.