Complex sentence: The captain and his crew also abandoned ship even though all passengers had not been evacuated and many passengers were still onboard the burning ship after it was towed to harbour (this was not deliberate as the captain and crew were unaware how many passengers had escaped).
Split into simpler sentences: The captain and his crew also abandoned ship, even though all passengers had not been evacuated. Many passengers were still onboard the burning ship after it was towed to harbour (this was not deliberate as the captain and crew were unaware how many passengers had escaped).