Our recent works reveal that the cross-basin transport, heat redistribution and corresponding mechanism in the subsurface and deeper ocean (SDO, 300-2000m) of key regions are playing an important role as planetary heat sink varies during the global surface warming accelerations and “hiatus”, i.e., Southern Oceans, Sub Polar North Atlantic, and Western Pacific Warm Pool, the latter two are considered as the “Switch” and “Engine” of the global climate change, respectively. The so-called “hiatus” refers to the temporary slow-down of the global mean surface temperature (GMST) warming during 1998-2013, caused by heat redistribution and storage in the SDO. Identifying the mechanisms, key regions and their role in cross-basin transport and the linkage of the “switch” and “engine” of the climate change has been hotly debating within scientific communities. Our research shed light upon our understanding of the climate change dynamics and cross-basin transport. Linking together by the Indonesia Through Flow, Agulhas Current/Leakage and Indian Ocean, our studies show that the ocean heat variability is highly inhomogeneous during the “hiatus”. Due to poor data coverage, it is not conclusive which ocean basin is more or most important yet. Instead of counting how many joules of heat stored in each ocean basin, it is more imperative to study the physical mechanisms for heat uptake in different key regions and cross-ocean transport by deep ocean remote sensing, which is a promising technique capable to fill the data gap of the thermal and dynamic structure in the SDO.