The Round 2 is supposed to be diveable up to 30 meters. The Time 2 is merely resistant, so you can't dive or swim with it.

While the original announcement just said ipx8, the chart at https://repebble.com/watch says the target for both watches will be 30 meters (search for "30m"). (note: even though the duo is rated for 20m, they've said specifically not to dive with them: https://ericmigi.com/blog/pebble-2-duo-is-in-mass-production)