Bawean is a small island in the Java Sea, about 150 km north of Surabaya. It is still more local than polished: ferries set the pace, motorbikes are the usual way around, and most of the island is a knot of green volcanic hills rising above fishing villages and narrow beaches.
The island has a character of its own. Baweanese language and migration links tie it to Madura, Java, Malaysia, and Singapore, while the old nickname "Island of Women" comes from the long pattern of men leaving for work elsewhere. For travelers, the pull is simpler: Lake Kastoba in the island's interior, waterfalls on the wooded slopes, offshore sand islands, and the last home of the critically endangered Bawean deer.
Bawean is not an easy add-on. The fast boat from Gresik takes several hours and schedules can be weather-sensitive, so it deserves more than a rushed day trip from the mainland. Go if you want a quiet Indonesian island where the sights are real, the infrastructure is modest, and the reward is moving slowly.