Thank you for your message and the interest you have expressed in Cartier.
We are delighted to learn of your interest in our creations. In response to your enquiry, may we kindly inform you that Cartier indeed increased the water resistance for some watchmaking creations, however, we are unfortunately unable to confirm the exact year or time frame, as this was many years ago.
In regards to the water resistance, we confirm that 8atm water resistance is enough resistance to shortly swim with. However, we always recommend to remove your watch if you would like to go swimming, in order to reduce any risks. But technically, it is possible for a timepiece with 8atm water resistance.
Should you decide to swim with your timepiece, we advise that you ensure that the crown of the watch is fully pushed against the case and that any push pieces (such as chronograph functions if applicable) are not used under water. This will stop any water entering the watch case.
More importantly, we recommend for all of our watches to be checked regularly which will enable you to determine whether or not it is sufficiently water-resistant. If not, the seals should be replaced. During normal use, we recommend having the seals replaced every 3 years, to guarantee maximum security.
We wish you a lovely afternoon and remain at your disposal for any further assistance.