In at least some embodiments, a disclosed subsea cable includes one or more floodable optical fiber conduits each having at least one tight buffered optical fiber for transporting optical signals. Each tight buffered optical fiber may have a relatively limited length. The subsea cable may further include multiple strength members contra-helically wound around or together with the one or more floodable optical fiber conduits. There may also or alternatively be included at least one hermetically sealed optical fiber conduit having at least one protected optical fiber spliced to one of the tight buffered optical fibers. At least some implementations splice each of the tight buffered optical fibers to corresponding protected fibers for the long-haul communications. Flooding of the floodable conduits may be provided via connectors at the subsea cable ends, via breakout locations where sensors are attached, and/or via vents in the conduit wall. Some method embodiments deploy the disclosed subsea cable designs in a body of water, putting the interior of at least one floodable optical fiber conduit in fluid communication with the body of water while supporting extended use for communicating signals, particularly in deep water where temperatures are relatively low. Because the floodable conduits have pressure-equalized interiors they may be formed from plastic or other materials that ease the process of attaching sensors to the subsea cables.