"I want to row round and see who that is.

Wait a moment, though." The oars below made some half-dozen strokes, and then were still again.
Once more there came the sound of something heavy dropped into the water.
"Someone is making soundings in the channel there," he said.

"Come." They went very quietly till they were round the point, then quickened their steps, and Michael spoke.
"That's the uncharted channel," he said; "at least, only the Admiralty have the soundings.

The water's deep enough right across for a ship of moderate draught to come up, but there is a channel up which any man-of-war can pass.

Of course, it may be an Admiralty boat making fresh soundings, but not likely on Boxing Day." "What are you going to do ?" asked Francis, striding easily along by Michael's short steps.
"Just see if we can find out who it is.