I’ve been asked if there are any undiscovered islands at Lake Baikal. Baikal is quite well-studied and according to open sources there are no undiscovered islands there at the moment. However, everything is changing)
To make my answer more complete, I decided to describe some islands of the Lake. There are different opinions on how many islands actually are at the Lake.
Wiki says that there are 27 islands at Lake Baikal.
The largest one is Olkhon Island, its length 71 km, width – up to 12 km, area – 730 square km. There is the deepest point – 1637 meters – not far from the outer side of island.
There are also Uskanyei Islands, a small archipelago of rocky shores in the middle of Lake Baikal near the Holy Nose Peninsula (Republic of Buryatia). There are 4 islands in the archipelago – Big Ushkaniy (the area of ??9.4 km²), the maximum height above the lake – about 210 meters, and Thin, Round and Long islands. They are covered with larch forest. There are Baikal Seal rookeries on the banks. Human impact is minimal, because these islands are part of the Trans-Baikal National Park. One needs permission to land for visiting Ushkaniye Islands.
Yarki Island is located at the north of Lake Baikal, its length is 20 km, and width from 10 to 200 meters. The island is rapidly destroying because of its sandy structure and the constant rise of water level in Lake Baikal.
The writer and Baikal researcher Vitaliy Bryanskiy in his book “Hello, Baikal!” (1989) says there are 35 islands at Lake Baikal. He suggests that Lake Baikal has also such islets as separate large stones, boulders, pebbles or clusters. Some of them have vegetation and nests with gulls’ eggs.
Currently, most of the islands of Lake Baikal are enlisted as natural monuments or included to the two national parks.