Endoscope

An endoscope, comprising:

• an insertion section including a conduit having a continuous inner surface, an inner diameter, and a longitudinal center axis, and,
• wherein the inner surface at a distal end of the insertion section comprises:
• a first projection provided at a first position,
• a second projection provided at a second position, and
• a first recess provided at a third position,
• wherein, in a longitudinal direction of the insertion section, the first position is different from the second position,
• wherein, in a direction perpendicular to the longitudinal center axis:
• a distance from the radially innermost surface of the first projection to a radially outermost surface of the first recess is a first distance,
• wherein the first distance is the same as the inner diameter of the conduit,
• wherein the inner surface at the distal end of the insertion section further comprises:
• a second recess provided at a fourth position,
• wherein, in the longitudinal direction of the insertion section, the first position is the same as the third position,
• wherein, in the longitudinal direction of the insertion section, the fourth position is the same as the second position,
• wherein, in a side cross-sectional view and relative to a baseline surface of the conduit:
• the first projection and the second projection are each protruded from the baseline surface, and
• the first recess and the second recess are each recessed from the baseline surface, and
• wherein, in the side cross-sectional view, the first recess faces the first projection and the second recess faces the second projection.