v3.26.3
Document and Entity Information - shares
 9 Months Ended
Sep. 30, 2026
Nov. 13, 2026
Document and Entity Information    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Sep. 30, 2026  
Document Fiscal Year Focus 2026  
Document Transition Report false  
Securities Act File Number 001-42692  
Entity Registrant Name Blue Water Acquisition Corp. III  
Entity Incorporation, State or Country Code E9  
Entity Tax Identification Number 33-2301550  
Entity Address, Address Line One 1012 Springfield Avenue  
Entity Address, City or Town Mountainside  
Entity Address, State or Province NJ  
Entity Address, Postal Zip Code 07092  
City Area Code 203  
Local Phone Number 489-2110  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company true  
Entity Central Index Key 0002050501  
Current Fiscal Year End Date --12-31  
Document Fiscal Period Focus Q3  
Amendment Flag false  
Units, each consisting of one Class A ordinary share, $0.0001 par value, and one-half of one redeemable warrant    
Document and Entity Information    
Title of 12(b) Security Units, each consisting of one Class A ordinary share, par value $0.0001 per share, and one-half of one redeemable warrant  
Trading Symbol BLUWU  
Security Exchange Name NASDAQ  
Class A ordinary shares, $0.0001 par value    
Document and Entity Information    
Title of 12(b) Security Class A ordinary shares, par value $0.0001 per share  
Trading Symbol BLUW  
Security Exchange Name NASDAQ  
Entity Common Stock, Shares Outstanding   25,983,000
Redeemable warrants, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50 per share    
Document and Entity Information    
Title of 12(b) Security Warrants, each whole warrant exercisable for one Class A ordinary share at an exercise price of $11.50 per share  
Trading Symbol BLUWW  
Security Exchange Name NASDAQ  
Class B ordinary shares    
Document and Entity Information    
Entity Common Stock, Shares Outstanding   6,325,000