Trinia is located in what it own people refer to as Avacia, an area that the rest of the world would call southern Longerath. It is bordered by the nations of Solelhada, Solanchatka, Saint Samuel, and Angliyaa. It has a short coastline on what is known internationally as the Dark Sea, on the opposite side of which are the nations of Bowdani and Davenport.
Trinia is in the southern hemisphere. Its capital is about twenty-four degrees south of the equator, placing it just outside the tropical zone.
Trinia is an irregularly shaped country. Its borders mostly follow lines established hundreds of years ago by treaty and warfare, generally independent of geographical features such as mountain ranges and rivers. There are no straight-line borders.
Trinia is mostly landlocked. The exception is a short coastline to the west, where Trinia reaches the Dark Sea. This is a major centre of population for Trinia, and is the site of the country's capital city, Kurin.
The climate of Trinia varies between different part of the country. On the whole, however, it is likely to be warm but not fully tropical. The northern parts of the country are, naturally, the warmest. As the prevailing winds are northwesterly, the rain shadow of the central mountain range means that the northern regions are also the driest, although no part of Trinia is a desert. The southern parts of the country are somewhat cooler and experience more rain.
The central feature of the country's topography is the Velamnoćul mountain range, which divides Trinia from east to west. Also signifcant are the smaller Jul and Gorŏlu ranges, as well as the southern reaches of the Black Mountains. Historically significant is the Torlon Gap, between the Velamnoćul and Jul ranges — this has traditionally been the main corridor between western and eastern Trinia.
Most of Trinia's population lives in or around the basins of the Vulni, Laţin, Isŭl, and Źelena rivers — the first flows to the sea in the west, with its delta being Trinia's only coastline, while the other three flow out of Trinian territory to the east.
The rivers provide fertile soil for agriculture, and most of the land around them is used for crop-growing. Further away from the main rivers, in the hills and on the Aḱănji plains, the land is more suitable for pastoralism — a large amount of land is used for grazing cattle, sheep, and sometimes goats.
In the central regions of Trinia, on the slopes of the Velamnoćul mountains and in the Torlon Gap, there are areas of dense forest. The largest of these are named the Merenŏlun, Ţuridin, Ućandis, and Ĕlarivin forests. Other significant forested area are in the Black Mountains and in the south of Armenar. The highest valleys and plateaus of the mountains are largely bare of vegetation except for a few hardy species of tussock grass, and the peaks are permantently snow-covered.
A certain amount of land is set aside for national parks, covering a wide range of terrain types. The largest such parks are on the slopes of the Velamnoćul mountains.