So in 1943, Germany had about 240 uboats, of which 118 were operational at sea, which was apparently their peak number during the war. How do you suggest they monitor the entire northern Atlantic like that, though? They were not reigning supreme in that sense.

The Soviets didn't have the type of Air Force that the Western Powers did. That said, they weren't very shy about hitting cities with artillery, or sacking them the old-fashioned way.

One thing people forget about naval warfare is that the ocean is really big. Technologies like radar only really came into their own during WWII, and a huge part of every admiral's job was actually finding the enemy fleet. It's one of the reasons why the Allies' code breaking advantage was so important.

Furthermore, the U-boat was a strategic weapon that was generally used to raid merchant shipping. If surface vessels could find U-boats, they were generally capable of winning the tactical engagement. Especially because the Western vessels often operated in flotillas that included weapons specifically designed to counter submersibles.

Edit: spelling.

The Russians were effectively out of range from German cities for a long time, since they had very few strategic bombers, preferring two engine bombers instead; those strategic bombers they did have mostly targeted cities around the Baltic, aiming for railway junctures, airports, and the like.

I don't think they ever did enough damage to be meaningful, though: the Russian strategic bombing regiment dropped 144,750 kilograms of ordinance total during 1941 (before losses basically grounded them,) while the US dropped 1,510,463 kilograms of bombs in a single raid on Toyko in 1945.

Unsurprisingly, when the Soviets decided they DID need something bombed, they would ask the Western Allies to do so, though this was generally rare.

Uboats stayed away from coasts b/c they were vulnerable to submarine spotter planes. The US and Britain used PBY-5s. There's other things like submarine nets, placing boats around each other to shield a boat. The other thing was German intelligence just wasn't very good compared to the allies. There's no German equivalent to cracking the Enigma machine.

Soviets did bomb and a lot of their pilot groups are very famous. There's lots of stories and media about the Night Witches. The Long Range Air Force (ADD) started bombing German cities in '42. Their tempo increased as the Soviet's progressed. I think it's mostly that media rarely focuses on Soviet air power. People seem to be more interested in their tanks.

The Soviet Union launched a number of bombing raids against Berlin in 1941 and 1942, by naval planes operating from Saarema island and by long range air force units. The last attack in 1942 involved 200 planes. The damage inflicted by the attacks was very moderate however and the Soviet planners decided their heavy bomber assets would be better employed against military targets closer to the front.

More on the Soviet bombing raids against Berlin

Shortly before the end of the war Berlin was again bombed by 111 Soviet planes.