Usually the books I feature in "Books Everyone Should Read" are available free as eBooks, but alas, not this time. You should read it anyway. Buy a copy (I have about six). You can almost always find it at used book sellers. Pick it up from the library. But get it. It's worth it.
On the surface, Watership Down seems to be a simple story about rabbits. It is far more than that. It is a complex alegory on the nature of society, of religion, of government, and of human (yes, human) nature. It is also an epic adventure in the spirit of the Odyssey, um... only with rabbits.
Not all of Richard Adams' books are as well crafted, but they all have some of the most beautifully crafted prose of the past fifty years. I have loved this book since I was a teen, wrote papers about it in college, taught it to High School English students, and I still think it is one of the best books ever written. Read it and let me know what you think.