We went down the river by water bus.
In summer, many people enjoy water sports on the lake.
A less central noun use referring to the area at or by the water; in modern everyday Japanese, 水辺 or 水際 is usually clearer for this meaning.
Depending on the context, 水上 can refer to the waterside or water's edge.
The boat is floating on the water.
A rescue operation was carried out on the water.
In that region, transportation methods for traveling across the water are well developed.
water transport; water carriage
water skiing