Snowman, I don't know what the holes are, but one of them probably somehow does work for depth. Extremely unlikely to be for speed though.
A depth guage would work by letting water into a tube wich would somehow move a float or liquid in a calibrated tube. Not sure how this happens since any sight tube made of glass would break if the pressure got to be too much. However, at 200 meters, I think the pressure would be approx 300 psi, and maybe glass can take that if it's thick enough. (1 atmos = 14 psi every 30 ft in depth adds another atmos 1 meter = 39" so 200m = 7800" divided by 12 = 650 feet divided by 30 = 21 atmospheres times 14 psi = 303 psi)
The way a boats speeometer works in most cases is that there's a small paddlewheel in a little depression in the side of the hull, in an area where the flow of water is not disturbed by propellers or rudders. (or dive planes) The paddles stick out only a fraction of an inch into the flow, but enough that the passing water spins it.
One of the paddles has a small magnet on it and every revolution, the magnet passes another magnet on the inside of the hull and causes it to register. The number of turns per second gives you the speed.
There's also some speedometers that work somewhat like an aircraft pitot tube, but that requires a hole in the very bow of the boat facing forward. The holes you show are on the side.
There will also be holes somewhere near the engine room since the diesels would be water-cooled. Even with a radiator, (which is typical of salt-water boats) the heat has to go somewhere. This is done by raw sea water going through a heat-exchanger at the radiator, and the raw water gets ejected mixed with the diesel exhaust to cool the muffler and exhaust pipes as well, while the radiator coolant is kept in a closed system with the engine itself.
Usually the raw water intake hole will look like a small blister on the side of the boat with holes in it to strain out any seaweed or marine organisms.