Zac Efron Hit Bottom of Swimming Pool On Dive, Ingested Water Into Lungs

Zac Efron's swimming pool incident started when he dove into the water ... the dive was so deep, he hit the bottom of the pool and ingested water into his lungs ... TMZ has learned. Sources close to the situation tell us Zac went for a swim with friends very early Saturday morning in Ibiza when he decided to take a dive. We're told Zac ingested a large amount of water into his lungs when his chest hit the bottom…