A sperm whale stranded off Indonesia's coast was on Saturday rescued by activists and the navy. The whale was tugged to a depth of 25 metres before it was freed in the ocean, the Jakarta Animal Aid Network (JAAN) said on Twitter. It had been stuck in shallow waters on a beach west of Java since Wednesday, attracting locals who hampered rescue efforts. A JAAN activist told DPA the whale might have been disoriented by an oil exploration rig. Sperm whales are easily recognized by their massive heads and prominent rounded foreheads. They have the largest brain of any creature known to have lived on Earth.