Wideband receivers hidden in beach umbrellas can triangulate walkie-talkie, satellite phone, or drone control signals. For Semecaelababa, this might reveal a hidden command post inland.
"Stay on him, Elias! If he hits the water, we lose the signal."
"Copy, Thorne," came the crisp voice of his handler, Sarah, over the comms. "Stay focused. The security detail is tight. Don’t let anything distract you."