You may as well ask if you stand on the coast of east Africa, the Arabian peninsular, Iran, west coast of India, or the southern tip of India, the west coast of Sumatra, the east coast of Madagascar, the Kerguelen Islands, the Maladives, Diego Garcia, or the west coast of Australia, how deep is the Indian Ocean?
Estimating the depth of a body of water from its nearby topographical features is impossible.
What distinguishes Lake Baikal, in Russia, from the great lakes of North America or Lake Victoria in Africa, or the Caspian Sea? The topographical features around Lake Baikal are not extraordinary and they give no hint as to the depth of Lake Baikal; yet it has a maximum depth of 1642 m and an average depth of 744 m. It is the deepest lake in the world.
What makes Lake Baikal so deep is it is a rift valley lake. The lake is associated with a rift valley that is pulling that part of the Asia apart. The same way the east African rift valley is pulling apart Africa.
Lake Malawi (Lake Nyasa), Lake Tanganyika and Lake Turkana are all lakes in the East African Rift. As with Lake Baikal, the depth of these lakes cannot be estimated from surrounding topology or size of the lakes - length, width or area.