have invested resources in studying the surface of other planets. we have only actually explored about 3% to 5% of our oceans. the rest remain s unexplored. web, the ocean is opaque, you can't see through it, so you need other instruments. believe it or not, there's more mountains in the ocean than on land. >> absolutely. >> and they're towering mountain ranges down there. >> how could the terrain impact searching for debris? the mountains are higher, i would imagine that makes things a lot more complicated. >> it does. in general in the ocean when you have rugged terrain, mountains, ridges, debris or acoustic signals, this black box trans t transmitransmi