Gemini 3 Deep Think
Google's extended-reasoning mode for the hardest math and science problems
Gemini 3 Deep Think is Google’s extended-reasoning mode for Gemini 3, built for the hardest math, science, and logic problems where a quick answer isn’t good enough. Rather than responding immediately, it explores multiple solution paths in parallel and checks its own logic before committing to an answer, which comes at the cost of much higher latency than Gemini 3 Pro. It scored 41.0 percent on Humanity’s Last Exam, more than 11 points ahead of GPT-5.1 on the same benchmark at the time. Access is gated behind Google’s AI Ultra subscription, which starts at $99.99 a month and requires the $199.99 tier specifically for Deep Think, so it isn’t reachable through the standard Gemini API the way Google’s other models are.