You need a hard wired antenna to get the signal out.
I use a Gopro Hero 3+ with an antenna to my phone. The wire antenna is just taped to the camera case and the back of the phone. Using the Gopro app, you have an underwater camera.
Here is the link to the vid my kid made on Gull:
https://youtu.be/SoyYyMKgb6g
I just used some u-bolts and mounted the camera to some 3/4" pvc jammed into the mud.