A flooded bin measurement system is provided that includes a submarine sampler for ascending and descending within a liquid of a bin and for measuring the depth of fluid at the submarine sampler's location. In one embodiment, the submarine sampler may ascend and descend along a vertical guide based on adjustments to it buoyancy compared with the liquid in the bin, which may be controlled manually and/or automatically. The measurement system may include a bubbler system for measuring hydrostatic pressure at the submarine sampler for determining its depth within the fluid of the bin. The submarine sampler may include a device having a hollow interior, an open bottom and an air supply line connected to the hollow interior. According to a further embodiment of the invention, the submarine sampler may be fixed to a line that is connected to a counterweight at its opposite end.