Wikia

AreasEdit

Deserted Island 孤島		Flooded Forest 水没林		Sandy Plains 砂原		Tundra 凍土

Volcano 火山		Misty Peaks 渓流		Great Desert 大砂漠		Underwater Ruin 海底遺跡

Tower 3		Sacred Land 神域		Tainted Sea 厄海

The Underwater Ruin, an Area which wasn't present in MHP3rd, returns in this game.
Monster Hunter 3 Ultimate uses MH3's version of the Flooded Forest rather than MHP3rd's version.
Tower 3 from Monster Hunter Freedom Unite reappears in MH3U.
The Misty Peaks Area is the only new Area from Monster Hunter Portable 3rd that returned.
A new Town, Port Tanzia, replaces Loc Lac City.
Tainted Sea is a new Area where hunters battle against Dire Miralis.

Areas
Villages & Towns	Kokoto Village \| Minegarde Town \| Jumbo Village \| Dondruma Town \| Pokke Village \| Moga Village Loc Lac City \| Yukumo Village \| Mezeporta Square \| Port Tanzia
General Regions	Forests \| Deserts \| Volcanoes \| Swamps \| Jungles \| Snowy Mountains
1st Generation	Forest and Hills \| Old Jungle \| Old Desert \| Old Swamp \| Old Volcano
2nd Generation	Snowy Mountains \| Jungle \| Desert \| Swamp \| Volcano \| Great Forest
3rd Generation	Deserted Island \| Flooded Forest \| Sandy Plains \| Tundra \| Volcano (3rd) \| Misty Peaks
4th Generation	Ruins Field \| Primeval Forest \| Underground Cave \| Unknown Sea of Trees\| Frozen Sea
Frontier Areas	Gorge \| Great Forest Peak \| Absolute Island \| Nest Hole \| Highland \| Competition Arena Interceptor's Base \| Tide Island \| Polar Sea
Special Areas	Tower \| Tower 2 \| Tower 3 \| Town \| Fortress \| Castle Schrade \| Battleground Snowy Mountains Peak Underwater Ruin \| Great Desert \| Sacred Land \| Polar Zone \| Lava Canyon \| Mountain Summit Tainted Sea
Arenas	Great Arena \| Moat Arena \| Arena \| Land Arena \| Water Arena \| Small Arena