A mast having a longitudinal axis and comprising: a base segment, a first mast segment and a second mast segment each comprising a modular, hollow tubular body having a circumferential outer wall (5, 26, 28, 30, 115) enclosing an axially extending cavity, the first mast segment is arranged between the base segment and the second mast segment and configured to be releasably connected to the base segment and the second mast segment, each of the base, first and second mast segment (13, 23, 25) further comprises a bearing structure for bearing the weight of the mast, at least the first mast segment further comprises: an internal bearing structure in the cavity, comprising: an axially extending inner cylinder connected via radially extending ribs to outer cylinder portions (71, 72) at first and second ends (73, 75) of the internal bearing structure, wherein said ribs axially extend from said first end to said second end, said internal bearing structure is surrounded by the circumferential outer wall axially extending from said first end to said second end, and the inner cylinder by a core wall of the inner cylinder encloses an axially extending core cavity for enabling cabling to pass through from the cavity of the base segment to the cavity of the second mast segment, wherein both the first end and the second end of the internal bearing structure further comprise an end cap (97, 98) provided with a respective extension shaft (107, 109), wherein the inner cylinder, the outer cylinder portions (71, 72) and the circumferential outer wall of the first mast segment enclose at least one axially extending compartment, and wherein the first mast segment further comprises at each of the first and second end (73, 75) a first and a second gasket (93, 101), which, in mounted position, are pressed between the circumferential outer wall and a respective end cap (97, 98), and the core wall and a respective end cap (97, 98) to seal said compartment. a base segment, a first mast segment and a second mast segment each comprising a modular, hollow tubular body having a circumferential outer wall (5, 26, 28, 30, 115) enclosing an axially extending cavity, the first mast segment is arranged between the base segment and the second mast segment and configured to be releasably connected to the base segment and the second mast segment, each of the base, first and second mast segment (13, 23, 25) further comprises a bearing structure for bearing the weight of the mast, at least the first mast segment further comprises: an internal bearing structure in the cavity, comprising: an axially extending inner cylinder connected via radially extending ribs to outer cylinder portions (71, 72) at first and second ends (73, 75) of the internal bearing structure, wherein said ribs axially extend from said first end to said second end, said internal bearing structure is surrounded by the circumferential outer wall axially extending from said first end to said second end, and the inner cylinder by a core wall of the inner cylinder encloses an axially extending core cavity for enabling cabling to pass through from the cavity of the base segment to the cavity of the second mast segment, wherein both the first end and the second end of the internal bearing structure further comprise an end cap (97, 98) provided with a respective extension shaft (107, 109), wherein the inner cylinder, the outer cylinder portions (71, 72) and the circumferential outer wall of the first mast segment enclose at least one axially extending compartment, and wherein the first mast segment further comprises at each of the first and second end (73, 75) a first and a second gasket (93, 101), which, in mounted position, are pressed between the circumferential outer wall and a respective end cap (97, 98), and the core wall and a respective end cap (97, 98) to seal said compartment. an internal bearing structure in the cavity, comprising: an axially extending inner cylinder connected via radially extending ribs to outer cylinder portions (71, 72) at first and second ends (73, 75) of the internal bearing structure, wherein said ribs axially extend from said first end to said second end, said internal bearing structure is surrounded by the circumferential outer wall axially extending from said first end to said second end, and the inner cylinder by a core wall of the inner cylinder encloses an axially extending core cavity for enabling cabling to pass through from the cavity of the base segment to the cavity of the second mast segment, wherein both the first end and the second end of the internal bearing structure further comprise an end cap (97, 98) provided with a respective extension shaft (107, 109), wherein the inner cylinder, the outer cylinder portions (71, 72) and the circumferential outer wall of the first mast segment enclose at least one axially extending compartment, and wherein the first mast segment further comprises at each of the first and second end (73, 75) a first and a second gasket (93, 101), which, in mounted position, are pressed between the circumferential outer wall and a respective end cap (97, 98), and the core wall and a respective end cap (97, 98) to seal said compartment.