Can someone tell me where the swings and cliffs are at D.Hollow?

[PAPutzback]

I am headed down there with five other boating families and would like to know where those places are. Has anyone mapped them?
Also what apps do people use to stay in touch with the other boaters when you take off to tube or ski while others are floating in a cove? Do you use the little walkie talkies or send text messages and hope someone gets a brief signal?

Are there any decent navigation apps for plotting destinations that can be shared between the other phones?