So far the only way to get any information about the interior of rocky planets was from the moment of inertia which is related to a planets mass distribution. This only allowed to estimate if a planet has a mantle and what the estimated thicknesses of the core and mantle are. Of course, other (remote sensing) methods like potential (gravity and magnetic) fields can also give more information about a planets interior. However, the only solid way to determine the layer interface and their depth and thicknesses is seismic imaging, a popular technique used to image Earth’s subsurface and interior.
One can notice the depth of the ocean floor, on a global scale, ranges between -2000 and -6000 meters. In some regions though like the Pacific exceed this range and reach 11 kilometers below the sea surface. One such region is the deepest point on Earth, the Mariana trench as shown below followed by a map for a perspective of its location.
One of the ways scientists are attempting to reduce greenhouse gases is to inject these gases into the ground. Specifically, they are testing injecting them, into basalt which is type of igneous rocks usually forming the first (rock) layer (sandwiched between the sedimentary & gabbro layers) in the oceanic crust basalt and in volcanic regions.
The above video features Iceland and its geothermal plants. Iceland is a heaven for geothermal energy as it lies along the Mid-Atlantic Ridge (MAR) (i.e. where Mid-Atlantic ocean floor is spreading apart in opposite directions forming a ridge). Most notably Iceland lies along the V-Shaped Reykjavik ridge (figure below; Google maps) which is part of the Norther MAR.
When ESA’s SMOS satellite was placed in orbit in 2009, it transpired that its signal was being interrupted by numerous illegal transmitters around the world. However, by working with national frequency protection authorities, 75% of these transmitters have now been shut down. Nevertheless, this is a laborious process and some regions, such as the Libyan coast and the eastern Mediterranean Sea, remain contaminated where mitigation strategies have not yet been successful. Source: ESA
Thanks to new processing techniques, information from ESA’s SMOS mission can be used to map salinity in the surface waters of the Mediterranean Sea. For example, daily maps can be created using DINEOF, which reduces noise and other sources of contamination. The image, which captures salinity on 3 March 2013, shows the fresher water from the Atlantic Ocean flowing through the Strait of Gibraltar into the Mediterranean Sea. Source: ESA