The primary challenge here is the nature of the seafloor rather than anything else. The bottom is not distinct, but consists of a deep layer of fine silt carried to the sea by rivers from the surrounding tropical islands (it is not open ocean, but an enclosed shallow inland sea) which is intermingled with both live and decaying micro-organisms that feed on the nutrients in this silt. The mud thickens as one goes deeper, but the top layer is practically of liquid consistency, any denser object will sink into it. Firm ground is several metres below the top of the mud, and any dense compact object will sink to the bottom. Probably all wreckage that was light enough or large enough to stick out of the mud has already been recovered, now the only way forward is to suck away the mud and search by feel, as visibility is next to zero during this process (and when suction stops, nearby mud flows in to fill the void). If done in a systematic way, this will eventually lead to the recovery of all wreckage, but it is a really tedious slow process.