To offer an alternative for supplying fresh water to people in distress in tropical seas before rescue or to garrison soldiers on a small reef, a portable solar-photovoltaic atmospheric water generator was designed and tested experimentally, and is composed of a water generating module, a water purifying module, a power supply and control module, and a buoyancy module. The results showed that the best water production rate of 460 mL/h was achieved when Tin = 27, RHin = 92%, Qa = 600 m3/h, with the desalination rate above 99.65%, proving itself a feasible solution as a portable desalination device. The daily water production can reach 5.52 L/d, which is more than twice the minimum quantity of the WHO drinking water standard (2.5 L/capita-day), and the energy consumption can be controlled under 200 W. The influences of major operating parameters on the device performance were analyzed and performance comparisons were carried out with the reported AWG products/prototypes. By integrating with a distress signal launcher and positioning module to shorten rescue time, the device has the potential to be employed as a small rescue platform for people in distress in tropical oceans, carried on board ship as a precaution.