Another Y Combinator Demo Day took place on Thursday, with this batch skewing far more toward deep tech than in past years. Tech Crunch asked early-stage VCs to name the hottest startups, compiling a list flagged by at least two investors as the buzziest. The tech felt "like science fiction," but valuations were notably more grounded than recent cohorts.

Top picks are listed alphabetically: Automarine builds nuclear-powered data centers floating at sea, co-founded by an MIT computer science and naval engineer and an MIT PhD in nuclear engineering, aiming to launch a gas-powered pilot by 2028 and transition to nuclear ships by 2032. It claims over $4 billion in customer interest through letters of intent. Dipole Labs develops energy-efficient high-speed optical networking hardware for AI data centers, allowing data to stay as light rather than converting to electricity.

Isengard Industries mass-produces jet-powered strike and counter-drones locally within allied countries, co-founded by a former Australian Army officer and a defense entrepreneur with $60 million in prior revenue. Lamb Labs creates custom inference chips with hardcoded AI model weights, dubbed Model Processing Units, to eliminate memory-bandwidth bottlenecks. Praxis AI collects real-world data to train robots, partnering with publicly traded companies and capturing video in over 150 environments.

Nori is building affordable robots to handle ever-expanding tasks.