Full of submerged reefs or sandbanks or shoals.
1We passed two nights at anchor in shoaly water off the beach.
2Yes ma'am the river is pretty shoaly right there.
3The numbers of turtles which were seen swimming in quiet shoaly bays passed on the road, also gave us much amusement.
4As we approached the island, numbers of the animals were seen coming to the surface to breathe, in a small shoaly bay.