Russia is the largest of the world’s ten largest countries by area with a Pacific Ocean coastline.
Russia ranks first globally by total area and reaches the Pacific through its Far Eastern territories. Its Pacific coast includes the Sea of Japan, the Sea of Okhotsk and the Bering Sea, with major coastal areas around Kamchatka, Sakhalin and Primorsky Krai.
Several other countries in the global top ten also touch the Pacific, including Canada, China, the United States and Australia. Russia is larger than each of them by total area, so it remains first within that group.
The Pacific coastline is geographically complex because marginal seas and island groups are closely connected to the ocean. This question concerns sovereign countries with Pacific access, not the length of their coastlines or the area of their Pacific waters.