SELECT
   id AS dive_id,
   to_char(start_time, 'YYYY:MM:DD HH:MM') AS start_time,
   to_char(end_time, 'YYYY:MM:DD HH:MM') AS  end_time,
   (extract('days' FROM NOW()) * 24) + extract('hour' FROM now()-start_time) || ':' || extract('minute' FROM now()-start_time) || ':' || extract('second' FROM date_trunc('second', now()-start_time))
AS
   elapsed_time
FROM
   checklist
ORDER BY
   id desc
LIMIT 1