Some feedback from Micheal McDonald at HYCOM re getdata:

I see that the code might be unnecessarily querying the same
.dds/.das [Dataset Descriptor Structure (DDS) & Dataset Attribute
Structure" (DAS)] repeatedly. Note: this does not change, ever, as it is a reanalysis product. So
from a network perspective, caching this .dds/.das in an array locally
once upon dataset open would cut down on a lot of unnecessary
client->server->client bandwidth for each query.

Not sure if this is something that can be changed whilst still making the code general for a range of data sources?