How old are you ?
That question may determine what you see in the optical illusion picture below by Sandro Del-Prete. If you are very young you will see nine dolphins at play. If you are not very young you will see a couple in an erotic embrace.

What is very young? I asked my 8 year old son what he saw and he told me he saw a man and woman, but we didn't explore details of what he saw. However it has been said that younger children don't have the context to see anything other than the dolphins.
You have been able to see the nine dolphins by now haven't you? No? Come on now get your mind up out of the gutter and look a little harder.
If it makes you feel any better it took me quite a while to see the dolphins. Once you find one the rest will be obvious.
I had many people find this site looking for the answer to 7 horses. I have an illusion on this site by Jim Warren that is called 7 horses. It became clear to me over time that many were coming here for the answer to the below illusion and not the painting by Jim Warren.

This painting is titled "Pintos" and was painted by Bev Doolittle. She had this to say about the creation of this painting.
"I was observing a small group of chestnut horses in a grassy meadow when I became aware that they were 'observing' me. This seemed like an interesting situation for a painting. I also thought it would be fun to have the horses observing you, the viewer, before you could find the horses! So I began to think of ways to camouflage them. The chestnut horses became Pintos, and the grassy meadow turned into a backdrop of rocks and snow." - Bev Doolittle
The reason people are confused is because there is one optical illusion site out there that states as fact that there are seven horses in the painting, but they don't bother showing you where they are. Well I am going do something very similar. I am going to give you the answer without actually pointing out each horse.
The answer is there are only five horses. The reason I am not pointing them out is given some time you can find the 3 adult horses the one colt and one foal.
It is only when someone says there are two extra horses that people are driven crazy and go searching the net for someone to show them the horses.
If anyone has information on this painting that shows me there are more than 5 horses please leave me a message on this post.
If you came here looking for the answer to "Pintos" a painting by Bev Doolittle of horses in the snow click here.
This painting is by Jim Warren. It is an illusion of a different type. One the most enjoyable paper activities I did as a kid was the hidden picture puzzles. Find the seven horses in this picture and relive a little part of your childhood.

Click on the picture to find the answers on the artist's site.
While your there take a look around it is well worth the visit.The artist had this to say about this painting
As a kid, I always enjoyed those drawings in activity books with the faces and animals hidden in it. But they were often too easy, even for your average half-witted 10 year old such as myself. So I painted "Seven Horses", where each horse is a little harder than the next to find, until the seventh, which is almost impossible unless you're Einstein, who is not alive. So if you find six, here is a hint for the seventh:
You didn't think I would quote his hint, did you?
This painting is by Jim Warren. It is an illusion of a different type. One the most enjoyable paper activities I did as a kid was the hidden picture puzzles. Find the seven dolphins in this picture and relive a little part of your childhood.

Click on the picture to find the answers on the artist's site.
While your there take a look around it is well worth the visit.
He has another site that you all might be interested in titled "
The Great Illusion" written & designed by Victor Kahn with paintings by Jim Warren
The intro reads:
"You have been invited here to experience another reality.
The reality of thoughts, words and surreal images
that are hidden from you ...within your own mind."
This is an optical illusion of a different type. One the most enjoyable paper activities I did as a kid was the hidden picture puzzles. Find the seven hearts in this picture and relive a little part of your childhood. I don't have the answers, but I did put down my guesses in the comments.

Copyright
Jim WarrenUsed w/permission
Update: I found the answers on the artist's site. This painting was done by Jim Warren click on the picture to go to the artist site for the answers. While your there check out the rest of his site it is well worth it.