u boat's Usage Examples:

In Egyptian mythology, the hennu boat or Sokar barque (also henu, Manuel de Codage transliteration: Hnw) was a symbol of the god Seker of Memphis.

Strépy-Thieu boat lift at Thieu in the municipality of Le Rœulx Ronquières inclined plane at Ronquières in the municipality of Braine-le-Comte Trent-Severn boat.

Muttukadu boat house (Tamil: முட்டுக்காடு படகுக் குழாம்) is a water sport facility on the East Coast Road at Muttukadu, Chennai, India, offering rowing.

Synonyms:

submersible, schnorkel, pigboat, snorkel breather, asdic, sonar, nuclear submarine, breather, schnorchel, escape hatch, snorkel, submersible warship, submarine, attack submarine, nuclear-powered submarine, periscope, sub, auxiliary research submarine, fleet ballistic missile submarine, nautilus, conning tower, echo sounder,

Antonyms:

surface ship, nonsubmersible, surface, overhead, defend,