On the first day, they started off doing one round of 30 minutes.
The team did ten more rounds on day one which took 10*30 = <<10*30=300>>300 minutes.
The total time they took circumnavigating the land on the first day is 300+30 = <<300+30=330>>330 minutes.
On the second day, they did 15 rounds, which took 30 minutes each, giving 15*30 = <<15*30=450>>450 minutes.
The total number of rounds took 330+450 = <<330+450=780>>780 minutes.
#### 780