Complex sentence: In May 2017 HMS Monmouth a type 23 British frigate stopped and searched a fishing boat in the Indian Ocean discovering 455kg of cannabis and 266kg of heroin.
Split into simpler sentences: In May 2017, the HMS "Monmouth", a type 23 British frigate, stopped and searched a fishing boat in the Indian Ocean. The "Monmouth" discovered 455kg of cannabis and 266kg of heroin.