There was a program in UUSR, years ago, for large jet freighters using over-wing engines and wings designed for ground-effect flying. The concept was fuel economy because of the ground effect. It was a flying boat, so coast to coast routes over water. Slowish speed and using ground effect met not so powerful or heavy engines.
I can't remember the max payload, but there were different sizes of craft. Whatever happened to it?
It sounds like you're speaking of the
Ekranoplan. Some are still around, most on a much smaller scale than that of the
Caspian Sea Monster which may be the craft you are referring to.
It was basically built as a troop transport, though could have served other purposes. It wasn't that slow at all, as marine vessels go, and during its time of existence it posed a bit of a quandary for the IMO as to how to regulate a +400 km/h vehicle that was intended to co-exist with regular ship traffic.
As to what happened to it, it pretty much ran out of steam when the Soviet Union came down. It probably wasn't that practical or economical or efficient for most purposes (like the Airlander?). Nevertheless, a very fascinating venture (like the Airlander).