Complex sentence: It was renamed to Antipodes and operated as a tourism sub until 2004, taking thousands of tourists to the bottom of fiords of Milford Sound, reaching depths of 930 feet.
Split into simpler sentences: It was renamed to Antipodes at this time and operated as a tourism sub until 2004. There, Antipodes took thousands of tourists to bottom of fiords of Milford Sound, reaching depths of 930 feet.