40093
Due to the often fluctuating winter temperatures between above and below freezing , the saltwater ice of the Baltic Sea can be treacherous and hazardous to walk on , in particular in comparison to the more stable fresh water-ice sheets in the interior lakes .
 Baltic Sea
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Baltic Sea