v3.25.2
Cover Page
6 Months Ended
Jun. 30, 2025
Document Information [Line Items]  
Document Type 6-K
Entity Registrant Name C3is Inc.
Entity Central Index Key 0001951067
Document Period End Date Jun. 30, 2025
Amendment Flag false
Current Fiscal Year End Date --12-31
Document Fiscal Year Focus 2025
Document Fiscal Period Focus Q2