A unique package tour on Okinawa's Ishigaki Island for soon-to-be-married couples is creating a buzz.

The Ishigaki Municipal Government and travel agency H.I.S. Co. have teamed up to offer a proposal for couples: travel across the island, scale a steep cliff and dive into the sea — and then register your marriage.

Dubbed "the world's most challenging marriage registration tour," the idea is for couples to brave a string of difficult missions together to test their bond — and strength — to make tying the knot more memorable.