They'll be all right.

They can't go very far from home." "But I always dread some accident," said Mrs Burnet.
"Yes, my dear, you are always inventing something, and have been ever since Vince broke his leg." "Through going into dangerous places," said Mrs Burnet.
"Well, yes, that was from a cliff fall; but he might have done it from tumbling off a wall or over a chair." Just when this conversation was taking place the boys were slowly trudging home from their "retreat," as they called it--coming by a circuitous way, for the fact was very evident that old Daygo did spend a good deal of time in watching the boys' proceedings, and Vince was strongly of opinion that he suspected their discovery.
But Mike was as fully convinced to the contrary.
"He has no idea of it, I'm sure; but he is curious to know where we go.
The old chap always talks as if the island belonged to him.

He'd better not interfere with it if he does find out; but, I say, fancy old Daygo scrambling down through that passage.

I should like to see him." "I shouldn't," said Vince, "especially after all we've done." For a month had glided away, and they had been pretty busy, during their many visits to the place, carrying all kinds of little things which they considered they wanted, with the result that the lanthorn and a supply of candles always stood in a niche a short distance down the passage; short ropes were fastened wherever there was one of the sharp or sloping descents, so that they could run down quickly; and in several places a hammer and cold chisel had been utilised so as to chip out a foothold.
In the caverns themselves there was a fireplace, a keg which they kept supplied with water, a small saucepan, a little frying-pan, and a common gridiron, all of which had been bought and brought for them by the skipper of the little smack which touched at the island like a marine carrier's cart once a week.
Then they had an axe and saw, and stored up driftwood for their fire; fishing lines and a good supply of hooks; a gaff and many other objects, including towels--for the pools in the outer cavern's mouth were now their regular places for bathing.
As the time went on the novelty of possessing such a curious secret place did not wear off.

On the contrary, the satisfaction it afforded them grew, the more especially that the journey to and fro had become much more simple, for they had picked out the easiest way through the oak wood, knew the smoothest path among the granite blocks, and were always finding better ways of threading the rugged chaos at the bottom of the ridge slope.
As far as they could see ahead it seemed to them that there was nothing more to discover, and they might go on keeping the place entirely to themselves till they were grown up.
But at sixteen or so we do not know everything.