Complex sentence: Due to a large boulder that was blocking the water that filled the hot springs the island lost its main attraction and Yohyo suffered tremendous financial problems since the tourists stopped coming, but after Ranma-chan destroyed the boulder the island regained its former glory.
Split into simpler sentences: Due to a large boulder that was blocking the water that filled the hot springs, the island lost its main attraction and Yohyo suffered tremendous financial problems since tourists stopped coming. However after Ranma-chan destroyed the boulder the island regained its former glory.