Complex sentence: When the boat has burst into flames Brunhild appears from below Siegfried's alter and kills herself with his sword, she collapses on top of Siegfried's body and the boat sinks into the river where the treasure hoard is shown having been thrown into the river.
Split into simpler sentences: When the boat has burst into flames Brunhild appears from below Siegfried's altar and kills herself with his sword. She collapses on top of Siegfried's body, and the boat sinks into the river where the treasure hoard is shown having been thrown into the river.