You will leave Ninh Binh and bike on southbound Highway 1A toward the towns of Tam Ðiệp, Bỉm Sơn, Hà Trung, Lèn, and Thanh Hóa.
This leg stretches only 63 km, a rather short leg and about a half-day bike ride. This is all the reason to visit some famous sites in Ninh Binh, such as the famous Tam Cốc grottoes or the world renown Phát Diệm cathedral church prior to biking to the city of Thanh Hóa. Each site will take the entire morning to tour. Tam Cốc grottoes sits on a river, and the visit is done via canoes chaperoned by locals. Phát Diệm cathedral church is a way away from the main part of town. The cathedral sits on a large stretch of land surrounded by many smaller buildings that are as equally rich in architectural design and work as the cathedral itself. It is probably reasonable to take a rest day off from biking to see both sites. Otherwise visit one in the morning, and continue biking to Thanh Hóa in the afternoon. The road from Ninh Bình to Thanh Hóa is flat with a few short hill climbs. If you leave by noon, you should be able to get into Thanh Hóa city before sun set.