My apologies, I misunderstood where you were attempting to add this data. We have a data construct called survey, but it is not created during single encounter submission.
I would recommend using “Observation” for this. It is a type of data point that researchers can use for anything they wish to define. You can designate a name like “Time In” or “Dive Time”, and a value to correspond to it. When you are using the encounter search feature you can search for a specific name and value like “Time In” “12:04” or instead just search for the name “Time In” and return all encounters that have any value for that name. I’ll include a screen shot of where this is found on the encounter page.
You cannot set these from the submit page, it must be done from the encounter page. You can add as many of them as you like.
There is also the Survey data construct we use to contain multiple Occurrences, which then contain Encounters of animals. This is what I was referencing above. I think this may be an overly complicated solution for your stated usage. If you like I can say more about this process as well in case there are other aspects you would like to use.
Hope this helps!