Complex sentence: On 3 June 1984, a woman named Linda Griffiths was sailing on the lake with her two children and a friend of theirs when she observed a patch of water, about 300 feet away from her, that suddenly began to churn violently.
Split into simpler sentences: On 3 June 1984, a woman named Linda Griffiths was sailing on the lake with her two children, and a friend of theirs. Then, she observed a patch of water, about 300 feet away from her, that suddenly began to churn violently.