SS Palo Alto "the cement ship"

I've have seen this ship and visited it for almost 25 years and I never knew whats it's purpose was, so I looked it up on wikipedia and heres what it says.

The Palo Alto was a concrete ship built as a tanker at the end of World War I. She was built by the San Francisco Shipbuilding Company at the U.S. Naval Shipyard in Oakland, California. She was launched on May 29, 1919, too late to see service in the war.[1] Her sister ship was the SS Peralta.
She was mothballed in Oakland until 1929, when she was bought by the Seacliff Amusement Corporation and towed to Seacliff State Beach in Aptos, California. A pier was built leading to the ship, and she was sunk a few feet in the water so her keel rested on the bottom. There she was refitted as an amusement ship, with amenities including a dance floor, a swimming pool and a café.
The company went bankrupt two years later and the ship cracked at the midsection. She was stripped of her fittings and left as a fishing pier. Eventually she deteriorated to the point where she was unsafe for even this use and was closed to the public. Today she remains at Seacliff Beach and serves as an artificial reef for marine life.
In spring of 2005, oil found on wildlife nearly two years earlier was traced back to the ship.[2] In September 2006, a clean-up project was started estimated at $1.7 million. No oil is known to have spilled into the ocean, but wildlife experts believe birds came into contact with oil by entering the ship's cracked hull while diving underwater for fish