If you are in hurry to cross over Amanohashidate, you can take a speedboat(5mins to cross Amanohashidate).
Prices are various, usually if you are a big group not that much cost difference with taking a sightseeing boat(12mins to cross Amanohashidate). There is a shared speedboat as well. If you prefer a longer journey, they have also different kinds of route to show you inland sea and the open sea.
Shared speed boat to cross Amanohashidate:700yen~/single