The Strashimirovo Marsh (Yatata, Aldansko marsh) is a protected area located on the southern bank of the navigable channel connecting Varna and Beloslav lakes, 1 km east of Beloslav and south of the village of Strashimirovo. It has a rich diversity of bird species in all seasons. 208 bird species have been identified on its territory, 62 of which are included in the Red Data Book of Bulgaria. Protected bird species such as the little cormorant, pink pelican, Dalmatian pelican, little bittern, night heron, black stork, white stork, etc. can be found.