There is no time slot booking.

your ticket is valid for the day according to openings times and affluence.

Travel time by train: 20 minutes.
Average time of a visit from 2 to 3 hours (including the journey). Please note that the visit time can be extended depending on the number of visitors.
The opening of the ice cave also depends on the weather conditions and the opening conditions are given every day.
The visit is forbidden to children under 1 year old.
The ticket for a child under 5 years old is free of charge, upon presentation of a proof of age, and is only available at the ticket office.
The Voyage Mer de Glace ticket allows you to make a round trip by train and gondola, and enjoy visits (ice cave, glaciorium, temple of nature).
The return can be used up to D+7.

Enjoy your visit