SDI/TDI — Scuba Diving International / Technical

SDI and TDI are training organizations that issue scuba certifications. SDI focuses on recreational diving, while TDI handles technical specialties like decompression or rebreathers. You will see these logos at shops in Koh Tao or Komodo because they follow a standardized curriculum. Most technical divers choose TDI since the agency provides deep-water training protocols for complex gas mixes. Many students find the progression logical.

Avoid assuming all agencies teach identical skills. I noticed in Cebu that some SDI instructors emphasize different buoyancy drills than others. Always check if your specific TDI technical certification is recognized by the local dive center before you fly. This prevents expensive retraining costs if a shop only accepts PADI or SSI credentials. Check your digital cards carefully.