Kaichu Doro and the four islands

Gulf Oil paid for the first Kaichu Doro in 1971 and 1972 as its side of the deal that brought an oil terminal to Henza, and today the four-lane causeway is how every car and bike reaches the islands beyond. This route starts at Umino Eki Ayahashi-kan in the middle of it, where the car park is big and the boathouse across the road rents bikes. From the Henza end you ride past the tank farm and onto Miyagi, then down a coast road to the Nuchima-su salt factory before the Ikei Ohashi carries you to the last island.

Most of the 272 m of climbing comes on Miyagi, whose western plateau stands about 100 m above the sea. Our line takes the coast road out and back, and one short pitch near the salt factory reaches 14.7%. An e-bike flattens it. Ikei sits low on a limestone shelf, and its beach gate at 13.7 km makes a natural place to turn.

Coming home, swing south across the Hamahiga Ohashi at 24.5 km and roll down into Hama village. The road runs on to Higa, where Shirumichu and Amamichu hold the cave and the tomb that Ryukyuan tradition gives to the creator deities Amamikyu and Shinerikyu. People still come to pray at both, so walk up quietly and leave room for anyone at worship.

Uruma's own model course starts at Katsuren Castle and crosses the Kaichu Doro, and it suggests a rental bike for Hamahiga. Starting at the castle adds the World Heritage gusuku to the day. The Tour de Okinawa island loop also uses the causeway on its second day, riding out to Henza and back. In winter the north-east monsoon sweeps across Kin Bay with nothing to stop it, so check the forecast the night before and ride on the calmest morning you have.